[Acute abdomen - a practical approach]. / Akutes Abdomen ­ ein praktischer Zugang.

CLINICAL PROBLEM: Acute abdomen describes a critical clinical condition which includes a heterogeneous group of clinical presentations. Several diseases require immediate surgical treatment. Therefore, fast radiological assessment is demanded. STANDARD RADIOLOGICAL METHODS: Stable patients presenting at the emergency department with acute abdominal pain require an abdominal x­ray, an ultrasound examination and/or a computed tomography (CT) scan, depending on the location and character of their pain. These standard radiological methods provide a quick differentiation between simple and complicated pathologies. Unstable patients should undergo immediate CT and, if positive, be sent directly to surgery. METHODICAL INNOVATIONS AND ASSESSMENT: The ongoing technical developments in the field of computed tomography allow a quick and detailed characterization of pathologic conditions of the abdominal organs. A structured approach, based on the analysis of typical radiological signs and patterns, combined with the evaluation of extra-abdominal findings helps to assign the observed imaging findings to specific diseases. RECOMMENDATION: A systematic 4­point approach for structured analysis of specific and nonspecific imaging features and common pitfalls aids to choose the correct radiological method and help to narrow the broad spectrum of potential differential diagnoses.

Dynamic 1.5-T vs 3-T true fast imaging with steady-state precession (trueFISP)-MRI sequences for assessment of velopharyngeal function.

OBJECTIVES: To compare the image quality of MRI scans produced with 1.5- and 3.0-T devices during functional test condition. METHODS: 65 MRI scans obtained with 1.5- (n = 43) or 3.0-T (n = 22) true fast imaging with steady-state precession (trueFISP) sequences from patients with a history of a cleft palate were evaluated. Two experts assessed the MRI scans, independently of each other, and blinded to the MRI technique used. Subjective ratings were entered on a five-point Likert scale. The median planes of three anatomical structures (velum, tongue and pharyngeal wall) were assessed in three functional states (at rest, during phonation of sustained "e" and during articulation of "kkk"). In addition, MRI scans taken during velopharyngeal closure were evaluated. RESULTS: Under blinded conditions, both observers (radiologist and orthodontist) independently rated the quality of 1.5-T scans higher than that of 3.0 T. Statistical analysis of pooled data showed that the differences were highly significant (p < 0.009) in 4 out of 10 test conditions. The greatest differences in favour of 1.5 T were observed for MRI scans of the velum. CONCLUSIONS: 1.5 T used with trueFISP may be preferable over 3.0-T trueFISP for the evaluation of the velopharyngeal structures in the clinical routine.

[Diseases of the hepatobiliary system as a cause of acute abdomen]. / Erkrankungen des hepatobiliären Systems als Ursache des akuten Abdomens.

Diseases of the liver and biliary system are common causes of acute abdominal pain and gallstone disease predisposes to cholecystitis and cholangiolithiasis. Sonography is the method of choice for the assessment of cholecystitis, whereas magnetic resonance cholangiopancreaticography (MRCP) is the standard technique to detect stones in the common bile duct. Multi-detector computed tomography (MDCT) is ideal for detection of associated complications, including abscess formation and gall stone ileus. Pyogenic, amebic and fungal liver abscesses are reliably diagnosed with MDCT which can also be used for interventional radiologic therapy of liver abscesses by percutaneous aspiration or drainage procedures. The second most common cause of liver rupture after blunt trauma is spontaneous rupture of hypervascular liver tumors (i.e., HCC, adenoma, angiosarcoma) and due to medical procedures. Multi-phase contrast-enhanced MDCT can reliably detect active bleeding to guide further therapy in these cases.

Gadoxate-enhanced T 1-weighted MR cholangiography: comparison of 1.5 T and 3.0 T.

PURPOSE: To qualitatively and quantitatively compare gadoxate-enhanced T 1-weighted MR cholangiography at magnetic field strengths of 1.5 T and 3.0 T. MATERIALS AND METHODS: A total of 40 patients with a non-dilated biliary system were retrospectively included in the study. T 1-weighted MR cholangiography 20 min after IV administration of 0.025 mmol/kg gadoxate (Primovist) was performed in 20 patients at 1.5 T and in another 20 patients at 3.0 T. Contrast-to-noise ratios (CNR) of the biliary system (common bile duct - CBD, right hepatic duct - RHD, left hepatic duct - LHD) compared to the periductal tissue were measured. Two radiologists also qualitatively assessed the visibility of the intrahepatic and extrahepatic biliary system using a six-point rating scale. The Mann-Whitney U-test and Pearson's correlation coefficient were used for statistical analysis. RESULTS: The CNRs of the intrahepatic and extrahepatic hepatic bile ducts were significantly higher at 3.0 T. Qualitative analysis showed a significant superiority for 3.0 T in the delineation of the intrahepatic biliary system (RHD, LHD, segmental ducts). CONCLUSION: Gadoxate-enhanced T 1-w MR cholangiography at 3.0 T offers better delineation of the intrahepatic biliary system in comparison to imaging at 1.5 T.

[Pancreas. Congenital changes, acute and chronic pancreatitis]. / Pankreas. Angeborene Veränderungen, akute und chronische Pankreatitis.

The pancreas develops from ventral and dorsal buds, which undergo fusion. Failure to fuse results in pancreas divisum, which is defined by separate pancreatic ductal systems draining into the duodenum. Risk of developing pancreatitis is increased in pancreas divisum. MR cholangiopancreatography (MRCP) is the technique of choice for detecting it non-invasively. Annular pancreas is the result of incomplete rotation of the pancreatic bud around the duodenum with the persistence of parenchyma or a fibrous band encircling (stenosing) the duodenum. Acute pancreatitis is usually caused by bile duct stones or alcohol abuse. Contrast-enhanced multi-detector row CT is the method of choice to assess the extent of this disease. In acute pancreatitis, the role of MRCP is mainly limited to finding bile duct stones in patients with suspected biliary pancreatitis. Chronic pancreatitis results in relentless and irreversible loss of exocrine (and sometimes endocrine) function of the pancreas. MDCT even shows subtle calcifications. MRCP is the method of choice for non-invasive assessment of the duct. Inflammatory pseudotumor in chronic pancreatitis and groove pancreatitis are difficult to differentiate from pancreatic cancer. In these cases, multiple imaging methods such as MDCT, MRI and endosonography including biopsy may be used to make a diagnosis.

Dynamic MR imaging of the gastroesophageal junction in healthy volunteers during bolus passage.

PURPOSE: To evaluate the feasibility of noninvasive dynamic fast magnetic resonance imaging (MRI) during swallowing in healthy volunteers, and to determine esophageal function at the gastroesophageal junction during swallowing. MATERIALS AND METHODS: A total of 20 healthy volunteers underwent MRI while swallowing in the supine position. Dynamic gradient-echo (GRE) sequences (balanced fast field echo [B-FFE]) were employed in three planes on a 1.5T unit using a phased-array body coil. Buttermilk spiked with gadolinium (Gd) chelate (40:1) for bolus passage was used as an oral contrast agent. We evaluated visualization of esophageal bolus transit, bolus transit time (BTT), peristalsis, identification of the gastroesophageal junction, and reflux during the Valsalva maneuver. RESULTS: The mean visible length of the esophagus was 16.2+/-5.3 cm in the sagittal view, and 13.8+/-4.9 cm in the coronal view. In the sagittal view the BTT was defined in 15 of 20 volunteers and was 7.6+/-1.4 seconds. The BTT in the coronal view was measured in seven of 20 volunteers and was 8+/-1.3 seconds on average. The axial view yielded higher scores (2.25) than the coronal (1.98) and sagittal (1.78) views for identification of the cardia and during the Valsalva maneuver. Bolus contrast was better displayed in the sagittal (2.2) view than in the coronal (2.08) or axial (1.73) planes. In six volunteers, gastroesophageal abnormalities, such as axial hernia, reflux, and nonperistaltic contractions, were identified. For statistical analysis we used the Friedman test and a one-way analysis of variance (ANOVA). CONCLUSION: The results indicate that dynamic MR swallowing is a feasible and reproducible technique that warrants further studies in patients.

[Pancreas. Part II: Tumors]. / Pankreas. Teil II: Tumoren.

Adenocarcinoma is the most common malignant pancreatic tumor, affecting the head in 60-70% of cases. By the time of diagnosis, approximately 80% of tumors are unresectable. Helical CT is very effective in detection and staging of adenocarcinoma, with a sensitivity of 76-92% for detection and an accuracy of 80-90% for staging, but it has limitations in the detection of small cancers (< or =2 cm). Multidetector CT (MDCT) has brought substantial improvements with its inherent 3D imaging capability. Mangafodipir-enhanced MRI is a problem-solving tool in the depiction of small cancers following an equivocal CT imaging result. Gadolinium-enhanced 3D gradient-echo MRI is helpful in the assessment of vascular invasion of cancer and in determining the etiology of cystic lesions. Serous cystadenoma is benign, has a lobulated contour and contains innumerable small cysts of 0.1-2 cm in diameter. Mucinous cystic neoplasms are unilocular or multilocular (fewer than six cysts), and the cyst diameter exceeds 2 cm. The presence of solid nodular components should alert the radiologist to suspect cystadenocarcinoma. Neuroendocrine tumors are mostly hypervascular. Diagnosis of insulinoma is a challenge: they are <2 cm in 90% of cases and mostly hypervascular at CT or MRI. A combination of contrast-enhanced MDCT, MRI, endosonography, and/or somatostatin receptor scintigraphy is used to detect these small tumors. This review summarizes the imaging features of the most common pancreatic tumors and discusses the limitations of CT, MRI and endosonography.

[Pancreas. Part I: congenital changes, acute and chronic pancreatitis]. / Pankreas. Teil I: Angeborene Veränderungen, akute und chronische Pankreatitis.

The pancreas develops from ventral and the dorsal buds, which undergo fusion. Failure to fuse results in pancreas divisum, which is defined by separate pancreatic ductal systems draining into the duodenum. Risk of developing pancreatitis is increased in pancreas divisum because of insufficient drainage. MR cholangiopancreatography (MRCP) is the technique of choice for detecting pancreas divisum non-invasively. Annular pancreas is the result of incomplete rotation of the pancreatic bud around the duodenum with the persistence of parenchyma or a fibrous band encircling (and sometimes stenosing) the duodenum. Acute pancreatitis is usually caused by bile duct stones or alcohol abuse. The Atlanta classification differentiates between mild acute and severe acute pancreatitis associated with organ failure and/or local complications such as necrosis, abscess or pseudocyst. Contrast-enhanced multi-detector row CT is the method of choice to assess the extent of disease. Balthazar et al.'s CT severity index assesses the risk of mortality and morbidity. In acute pancreatitis, the role of MRCP is mainly limited to finding bile duct stones in patients with suspected biliary pancreatitis. Chronic pancreatitis results in relentless and irreversible loss of exocrine (and sometimes endocrine) function of the pancreas. MDCT even shows subtle calcifications. MRCP is the method of choice for non-invasive assessment of the duct. Inflammatory pseudotumor in chronic pancreatitis and groove pancreatitis are difficult to differentiate from pancreatic cancer. In these cases, multiple imaging methods such as MDCT, MRI and endosonography including biopsy may be used to make a diagnosis.