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.

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.

[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.

[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.

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.

Treatment of gastrointestinal hemorrhage.

BACKGROUND: We assessed the value of selective arteriography in the diagnosis and management of acute gastrointestinal hemorrhage. METHODS: We reviewed the records of 107 consecutive patients who had gastrointestinal hemorrhage and underwent selective arteriography between January 1992 and October 2003: 10 had upper gastrointestinal bleeding, 79 had lower gastrointestinal bleeding, and 18 had varicose bleeding with portal hypertension. Selective embolization was attempted in 15 patients to obtain hemostasis. Angiographic findings were reviewed and prospective reports were compared with the final diagnosis and outcome. RESULTS: Of 129 angiographic studies, 36 correctly revealed the bleeding site and 93 were negative. Extravasation was seen in 24 cases at the level of stomach (n = 2), duodenum (n = 1), small bowel (n = 5), or colon (n = 16). Indirect signs of bleeding sources were identified in 12 patients (stomach in one, small bowel in four, large bowel in four, liver in three). Transcatheter embolization induced definitive hemostasis in 11 of 15 patients (73%), namely in the stomach (n = 2), small bowel (n = 3), colon (n = 7), and liver (n = 3). Three patients required surgery after embolization. CONCLUSION: Abdominal arteriography may localize gastrointestinal bleeding sources in approximately one-third of cases. Selective embolization may provide definitive hemostasis in most instances.

Specificity of SPIO particles for characterization of liver hemangiomas using MRI.

We investigated the specificity of superparamagnetic iron oxide (SPIO)-enhanced T1-weighted spin-echo (SE) magnetic resonance (MR) images for the characterization of liver hemangiomas. When imaging liver hemangiomas, which are the most frequent benign liver tumors, a method with very high specificity is required, which will obviate other studies, follow-up, or invasive diagnostic procedures such as percutaneous biopsy. Eighty-three lesions were examined by MR imaging at 1.5 T before and after intravenous injection of SPIO particles. Lesions were categorized as follows according to the final diagnosis: 37 hemangiomas, nine focal nodular hyperplasias (FNHs), 19 hepatocellular carcinomas (HCCs), and 18 metastases. Their signal intensity values were normalized to muscle and compared. The only lesions showing a significant increase in signal intensity ratio (lesion to muscle) on postcontrast T1-weighted SE images were hemangiomas (p < 0.001). The signal intensity ratio of hemangiomas increased on average by 70%. Based on receiver operating characteristic analysis and using a cutoff level of 50% signal increase, the specificity and sensitivity of SPIO-enhanced MR imaging for the characterization of hemangiomas would be 100% and 70%, respectively. The T1 effect of SPIO particles can help differentiate hemangiomas from other focal liver lesions such as FNHs, HCCs, and metastases and may obviate biopsy. When using SPIO particles for liver imaging, it is useful to add a T1-weighted sequence to T2-weighted images, thereby providing additional information for lesion characterization.

[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.

Successful treatment of a ruptured mycotic aneurysm of the ileocolic artery with transcatheter embolization and antibiotic therapy.

We report a case of mycotic aneurysm of the ileocolic artery due to Streptococcus bovis endocarditis and acute septicemia complicated by active hemorrhage, that was treated successfully with transcatheter embolization and subsequent intravenous antibiotic treatment. This case suggests that a mycotic aneurysm can be treated successfully by percutaneous embolization in an emergent situation (active bleeding, septicemia) even without previous antibiotic therapy.

Sialolithiasis and salivary ductal stenosis: diagnostic accuracy of MR sialography with a three-dimensional extended-phase conjugate-symmetry rapid spin-echo sequence.

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) sialography in detecting salivary glandular calculi and ductal stenoses. MATERIALS AND METHODS: In a prospective study, 64 salivary glands in 61 consecutive patients with acute or recurrent parotid or submandibular glandular swelling were examined by using three-dimensional (3D) extended-phase conjugate-symmetry rapid spin-echo (EXPRESS) MR imaging. Transverse and sagittal-oblique source images and maximum intensity projection images were obtained. All MR images were analyzed independently by two radiologists, without knowledge of the final diagnosis. The reference standard was conventional sialography, ultrasonography (US), and sialendoscopy with or without surgery in 31 glands and was conventional sialography and US in 33 glands. RESULTS: Final diagnoses included sialolithiasis (n = 23), sialolithiasis and stenosis (n = 9), stenosis without lithiasis (n = 11), early Sjögren syndrome without ductal stenosis (n = 2), ductal displacement (n = 3), and normal salivary glands (n = 16). The sensitivity, specificity, and positive and negative predictive values of MR sialography to detect calculi were 91%, 94%-97%, 93%-97%, and 91%, respectively. False-negative readings occurred due to calculi with a diameter of 2-3 mm in nondilated salivary ducts. Ductal stenosis was assessed, with a sensitivity of 100%, specificity of 93%-98%, positive predictive value of 87%-95%, and negative predictive value of 100%. Interobserver agreement was very good (kappa = 0.85-0.97). CONCLUSION: MR sialography with 3D EXPRESS imaging enables reliable prediction of salivary gland calculi and stenoses.

Blunt abdominal trauma in adults: role of CT in the diagnosis and management of visceral injuries. Part 2: Gastrointestinal tract and retroperitoneal organs.

Computed tomography plays an important role in the detection and management of blunt visceral injuries in adults. Current standard examination techniques enable detection of the majority of perforating or devascularizing bowel injuries, although diagnostic findings are often subtle and meticulous inspection is required. Computed tomography may demonstrate pancreatic contusions and lacerations and help in distinguishing minor traumatic lesions without involvement of the pancreatic duct (organ injury scale, grades I and II) from deep lacerations with ductal involvement (grades III and V). Computed tomography enables distinguishing renal contusions and minor cortical lacerations that can usually be managed conservatively (injuries of grades I-III) from corticomedullary lacerations and injuries of the major renal vessels (grades IV and V) that have a less favorable prognosis and more commonly require surgical repair. In addition, CT is well suited for the detection of active renal hemorrhage and guidance of transcatheter embolization treatment and delineation of preexisting benign or malignant pathologies that may predispose to posttraumatic hemorrhage. The radiologist's awareness of the diagnostic CT findings of abdominal visceral injuries as well as their clinical and surgical implications are important prerequisites for optimal patient management.

Blunt abdominal trauma in adults: role of CT in the diagnosis and management of visceral injuries. Part 1: liver and spleen.

Computed tomography is now widely used in the initial diagnostic workup of adult trauma victims with suspected intra-abdominal injuries. We review the role of CT in the detection and management of blunt visceral injuries in two parts. In the first part we discuss general aspects of performing CT in the setting of abdominal trauma and the diagnostic findings of intra-abdominal hemorrhage and blunt hepatic and splenic injuries. Hepatic and splenic injuries can be detected by means of CT with a high accuracy. The vast majority of hepatic injuries can be successfully managed conservatively, even when CT demonstrates parenchymal damage of more than three segments and major hemoperitoneum. Delayed complications, e. g., formation of biloma or a false aneurysm, can be readily detected on repeat CT studies, although they are quite uncommon. The outcome of conservative treatment of splenic injuries remains unpredictable because delayed splenic rupture may occur even when initial CT shows only minor parenchymal lesions and little or no intraperitoneal hemorrhage.

Long-term results of the Simon nitinol inferior vena cava filter.

The aim of this study was to evaluate the clinical efficacy, mechanical stability, and safety of the Simon nitinol inferior vena cava filter (SNF). The SNF was inserted in 114 consecutive patients at two institutions for prophylaxis of pulmonary embolism (PE). Clinical follow-up data were obtained retrospectively on all patients, and 38 patients underwent a dedicated radiologic follow-up protocol consisting of abdominal radiography, Doppler sonography, and CT. There was no immediate complication following filter insertion. Fifty patients died, on average, 5.6 (1-23) months after filter insertion, and 64 patients were alive, on average, 27 (3-62) months after filter insertion. Recurrent pulmonary embolism was documented in 5 patients (4.4 %) but originated distal to the filter in 1 patient. Deep venous thrombosis (DVT) was documented in 5.3 %, thrombosis at the access site in 3.5 %, and thrombosis of the inferior vena cava in 3.5 %. The rate of thromboembolic complications was similar in patients who did receive long-term anticoagulation and in those who did not. Radiologic follow-up showed no filter migration after, on average, 32 (5-62) months. A CT examination showed that struts of the SNF had penetrated the vena cava in 95 %, and were in contact with adjacent organs in 76 %; however, there were no clinical symptoms attributable to the filter. Filters were in an eccentric position in 63 % and partial filter disruption was found in 16 %; however, this did not affect filter function. The rate of recurrent pulmonary embolism after insertion of the SNF is 2.4 % per patient per year. Regardless of long-term anticoagulation, the rate of caval thrombosis is acceptably low. Except for occasional access-site thrombosis, no other filter-related morbidity was observed.

Choledocholithiasis and bile duct stenosis: diagnostic accuracy of MR cholangiopancreatography.

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) cholangiopancreatography for detecting bile duct calculi and stenosis. MATERIALS AND METHODS: At MR cholangiopancreatography, 108 patients suspected of having bile duct calculi or stenosis were examined with two-dimensional fast spin-echo MR sequences and respiratory gating. On the basis of findings at surgery and/or intraoperative, endoscopic retrograde, and/or percutaneous cholangiography, final diagnoses were normal bile ducts (n = 38), choledocholithiasis (n = 23), Mirizzi syndrome (n = 3), benign or malignant bile duct stenosis (n = 40), choledochal cyst (n = 1), and bile duct dilatation without calculi or stenosis (n = 3). MR cholangiopancreatographic images were analyzed retrospectively by three reviewers who were unaware of final diagnoses. RESULTS: Choledocholithiasis was diagnosed with a sensitivity of 88%-92% and a specificity of 91%-98%. False-negative readings occurred because small or impacted calculi at the distal common bile duct or ampulla were difficult to detect or distinguish from stenosis. Bile duct stenosis was diagnosed with a sensitivity of 93%-100% and a specificity of 98%. Presence or absence of bile duct abnormality was assessed with a sensitivity of 97%-99% and a specificity of 95%-97%. Interobserver agreement was very good (kappa = 0.86-0.96). CONCLUSION: With MR cholangiopancreatography, bile duct calculi and stenoses can be diagnosed with high accuracy and good interobserver agreement.

Ablation of hepatocellular carcinoma by percutaneous ethanol injection: imaging findings.

Since PEI is a treatment based on imaging techniques, the radiologist should be familiar with the various findings that may be observed after PEI on US, CT, and MR images immediately after treatment and during later follow-up. Although US is well suited for performing PEI, contrast-enhanced CT currently is the most commonly used imaging method to evaluate the effect of PEI. Residual, nodular areas of contrast enhancement correlate well with residual tumor and warrant additional treatment. Although the findings on MR images obtained after PEI are more complex, MR imaging may be used as an alternative to CT.