[Differential diagnosis of gallbladder abnormalities : Ultrasound, computed tomography, and magnetic resonance imaging]. / Differenzialdiagnose von Befunden an der Gallenblase : Ultraschall, Computertomographie und Magnetresonanztomographie.

CLINICAL ISSUE: Due to the high prevalence of clinically suspected cholecystitis or cholecystolithiasis the gallbladder is one of the organs examined the most by imaging. STANDARD RADIOLOGICAL METHODS: In most clinical settings ultrasound is the primary imaging method because of its wide availability, speed and superior spatial resolution. In cases of ambiguous findings or potential complications computed tomography (CT) and magnetic resonance imaging (MRI) are used. METHODICAL INNOVATIONS: When specific problems arise these imaging modalities may be enhanced by special techniques, e. g. contrast-enhanced ultrasound or dual-energy CT, and specific MRI sequences. PERFORMANCE: Special variants of cholecystitis, such as xanthogranulomatous cholecystitis and adenomyomatosis, may pose a particularly difficult diagnostic problem as they may resemble other diseases. Sequelae of cholecystolithiasis, such as the Mirizzi syndrome and acute bowel obstruction, may complicate the imaging algorithm as the location and the symptoms shift. Cases of neoplastic diseases of gallbladder cancer and other malignancies require a broad spectrum of imaging modalities. ACHIEVEMENTS: Although the gallbladder can easily be examined with ultrasound, some cases require a more thorough ultrasound examination. In some cases only a combination of multiple imaging modalities yield the diagnosis. Further developments regarding technical issues and the diagnostic algorithm can be expected. PRACTICAL RECOMMENDATIONS: Ultrasound is the best first imaging modality. In cases of ambiguous findings or clinical complications CT or MRI are recommended.

ESGAR consensus statement on liver MR imaging and clinical use of liver-specific contrast agents.

OBJECTIVES: To develop a consensus and provide updated recommendations on liver MR imaging and the clinical use of liver-specific contrast agents. METHODS: The European Society of Gastrointestinal and Abdominal Radiology (ESGAR) formed a multinational European panel of experts, selected on the basis of a literature review and their leadership in the field of liver MR imaging. A modified Delphi process was adopted to draft a list of statements. Descriptive and Cronbach's statistics were used to rate levels of agreement and internal reliability of the consensus. RESULTS: Three Delphi rounds were conducted and 76 statements composed on MR technique (n = 17), clinical application of liver-specific contrast agents in benign, focal liver lesions (n = 7), malignant liver lesions in non-cirrhotic (n = 9) and in cirrhotic patients (n = 18), diffuse and vascular liver diseases (n = 12), and bile ducts (n = 13). The overall mean score of agreement was 4.84 (SD ±0.17). Full consensus was reached in 22 % of all statements in all working groups, with no full consensus reached on diffuse and vascular diseases. CONCLUSIONS: The consensus provided updated recommendations on the methodology, and clinical indications, of MRI with liver specific contrast agents in the study of liver diseases. KEY POINTS: • Liver-specific contrast agents are recommended in MRI of the liver. • The hepatobiliary phase improves the detection and characterization of hepatocellular lesions. • Liver-specific contrast agents can improve the detection of HCC.

Preoperative evaluation of colorectal liver metastases: comparison between gadoxetic acid-enhanced 3.0-T MRI and contrast-enhanced MDCT with histopathological correlation.

OBJECTIVES: The aim of this prospective study was to compare the diagnostic performance of 64-row MDCT and gadoxetic-acid-enhanced MRI at 3.0 T in patients with colorectal liver metastases in correlation with histopathological findings. METHODS: Lesions detected at MDCT and MRI were interpreted by three blinded readers and compared with histopathological workup as the term of reference. Two subgroups of lesions were additionally evaluated: (1) metastases smaller than 10 mm and (2) lesions in patients with and without steatosis of the liver, assessed histopathologically. RESULTS: Surgery and histopathological workup revealed 81 colorectal liver metastases in 35 patients and diffuse metastatic involvement in 3 patients. In a lesion-by-lesion analysis, significant sensitivity differences could only be found for reader 1 (P = 0.035) and reader 3 (P = 0.003). For segment-based evaluation, MRI was more sensitive only for reader 3 (P = 0.012). The number of false-positive results ranged from 3 to 12 for MDCT and 8 to 11 for MRI evaluation. In the group of small lesions, the sensitivity differed significantly between both methods (P = 0.003). In patients with hepatic steatosis, MRI showed a trend toward better performance than MDCT, but without statistical performance. CONCLUSIONS: The 3.0-T MRI with liver-specific contrast agents is the preferred investigation in the preoperative setting, especially for the assessment of small colorectal liver metastases. KEY POINTS: • Potential surgical treatment requires accurate radiological assessment of colorectal liver metastases • Magnetic resonance imaging with gadoxetic acid is the preferred imaging investigation. • MRI is better than multidetector CT for detecting small liver metastases.

Gadoxetic acid-enhanced 3.0 T MR imaging versus multidetector-row CT in the detection of colorectal metastases in fatty liver using intraoperative ultrasound and histopathology as a standard of reference.

OBJECTIVE: To compare the diagnostic value of gadoxetic acid-enhanced MRI at 3.0 T with 64-row MDCT in the detection of colorectal liver metastases in diffuse fatty infiltration of the liver after neoadjuvant chemotherapy. METHODS: Twenty-three patients with colorectal liver metastases and at moderate to severe steatosis (25-90%) underwent prospectively preoperative tri-phasic MDCT (Somatom Sensation 64, Siemens) and gadoxetic acid-enhanced MRI (3-T Magnetom Trio, Siemens). All patients underwent surgical resection of liver metastases. Intraoperative ultrasound (IOUS) was carried out, which served as the standard of reference, together with histopathology. RESULTS: Overall, 68 metastases (range, 0.4-6 cm; 31/68 metastases [46%] ≤ 1 cm) were found at histology. MDCT detected 49/68 lesions (72%), and MRI 66/68 (97%, p < 0.001). For lesions ≤ 1 cm, MDCT detected only 13/31 (41.9%) and MRI 29/31 (93%, p < 0.001). Eight false-positive lesions were detected by MDCT, seven small lesions by MRI. There was no statistically significant difference between the two modalities in the detection of lesions > 1 cm (p = 0.250). IOUS detected all metastases and revealed two false-positive diagnoses. CONCLUSION: Gadoxetic acid-enhanced 3.0 T MRI is superior to 64-row MDCT in detecting colorectal liver metastases ≤ 1 cm during preoperative staging in patients with liver steatosis. A combination of MRI and IOUS may further improve the outcome of surgical treatment.

Is there a role for dynamic swallowing MRI in the assessment of gastroesophageal reflux disease and oesophageal motility disorders?

OBJECTIVES: To evaluate the diagnostic value of dynamic MRI swallowing in patients with symptoms of Gastroesophageal Reflux Disease (GERD). METHODS: Thirty-seven patients (17 m/20f) with typical signs of GERD underwent MR swallowing in the supine position at 1.5 T with a phased-array body coil. Using dynamic, gradient echo sequences (B-FFE) in the coronal, sagittal and axial planes, the bolus passages of buttermilk spiked with gadolinium chelate were tracked. MRI, pH-metry and manometry were performed within 31 days and results were compared. RESULTS: MRI results were concordant with pH-metry in 82% (23/28) of patients diagnosed with abnormal oesophageal acid exposure by pH-metry. Five patients demonstrated typical symptoms of GERD and had positive findings with pH monitoring, but false negative results with MRI. In four of six patients (67%), there was a correct diagnosis of oesophageal motility disorder, according to manometric criteria, on dynamic MRI. The overall accuracy of MRI diagnoses was 79% (27/34). A statistically significant difference was found between the size of hiatal hernia, grade of reflux in MRI, and abnormal acid exposure on pH-monitoring. CONCLUSIONS: MR fluoroscopy may be a promising radiation-free tool in assessing the functionality and morphology of the GE junction. KEY POINTS: • Swallowing MRI can assess anatomy and function of the gastroesophageal-junction • Swallowing MRI can help identifying reflux and motility disorders • Definition of the size of hiatal hernias is possible in all three planes in MR. • Short duration of swallowing MRI enables its application in routine clinical practice.

Liver metastases.

Liver metastases are a very common site of distant metastases. Detection and accurate characterization of liver metastases is of importance to guide therapy. A variety of imaging modalities such as US (including contrast agents), MDCT, MRI with liver -specific contrast agents and PET/CT are available for this purpose. This review presents imaging techniques and summarizes the current knowledge, how the different imaging modalities should be used.

[Benign focal hepatic lesions]. / Benigne fokale Leberläsionen.

A profound knowledge of the various benign focal hepatic lesions and selection of the most suitable radiological examination modality is essential for achieving an accurate characterization of a hepatic lesion and in turn will determine the further patient management. This will avoid unnecessary agitation to both patient and the referring clinician and limits time-consuming, costly and risky biopsies to an absolute minimum. The following article will discuss the typical and atypical appearances of the most frequent and clinically relevant benign focal hepatic lesions with ultrasound, computed tomography and magnetic resonance imaging.

[New developments in MRI of the liver]. / Neuere Entwicklungen der Leber-MRT.

Radiology has gained an exceptional position in medicine because a correct diagnosis is the most crucial issue in determining an accurate and personalized therapeutic strategy. This has a direct influence not only on the individual patient but also on the socio-economic aspects of healthcare services in terms of shortening the time interval to establish a diagnosis and to avoid risk-associated invasive diagnostic methods or long-term, cost-intensive follow-up. Magnetic resonance imaging (MRI) is an excellent example of this which due to continuous technological developments and emerging techniques allows a non-invasive diagnosis of the different hepatic diseases. In this article, we illustrate the direct correlation between the recent technical advances in MRI, such as 3.0 T, diffusion-weighted imaging, perfusion imaging, spectroscopy, texture analysis and MR elastography and obtaining a confident non-invasive diagnosis of focal and diffuse liver diseases.

[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.

[Peritoneum and mesenterium. Radiological anatomy and extent of peritoneal diseases]. / Peritoneum und Mesenterium: Radiologische Anatomie und Ausbreitungswege intraabdomineller Erkrankungen.

The abdominal cavity is subdivided into the peritoneal cavity, lined by the parietal peritoneum, and the extraperitoneal space. It extends from the diaphragm to the pelvic floor. The visceral peritoneum covers the intraperitoneal organs and part of the pelvic organs. The parietal and visceral layers of the peritoneum are in sliding contact; the potential space between them is called the peritoneal cavity and is a part of the embryologic abdominal cavity or primitive coelomic duct. To understand the complex anatomical construction of the different variants of plicae and recesses of the peritoneum, an appreciation of the embryologic development of the peritoneal cavity is crucial. This knowledge reflects the understanding of the peritoneal anatomy, deep knowledge of which is very important in determining the cause and extent of peritoneal diseases as well as in decision making when choosing the appropriate therapeutic approach, whether surgery, conservative treatment, or interventional radiology.

[Diseases of the peritoneum and mesenterium]. / Erkrankungen von Peritoneum und Mesenterium.

Peritoneal diseases can be seen in the different imaging modalities either as fluid collections or solid tumors along the ligaments, mesenteries, and spaces of the peritoneal cavity. The broad spectrum of different abnormalities includes inflammatory, infectious, traumatic, and neoplastic diseases. In this article, a large variety of peritoneal abnormalities such as ascites, peritonitis, intraperitoneal hemorrhage, and both primary and secondary peritoneal tumors are discussed. The different imaging modalities, characteristic radiological features, and typical pathways of anatomic spread are explained.

[Benign neuroendocrine and other rare benign tumors of the pancreas]. / Benigne neuroendokrine und andere seltene benigne Tumoren des Pankreas.

Neuroendocrine tumors (NET) of the pancreas are rare neoplasms, which arise from cells of the islets of Langerhans. The most common NET are the insulinoma, gastrinoma and hormone inactive NET. Very rare entities are the schwannoma, leiomyoma, teratoma, intrapancreatic lipoma, hemangioma and the intrapancreatic accessory spleen. Essential for therapy, which in most cases is difficult, are an exact localization and various modalities of imaging diagnostics.

[CT colonography: pathologic findings and pitfalls]. / CT-Kolonographie: Pathologische Befunde und Pitfalls.

Thin-section multidetector-row computed tomographic (MDCT) colonography is a powerful tool for detection and classification of colonic lesions. It is based on a helical thin-section (0.75-2 mm) CT dataset of the cleansed and air-distended colon. 2D and 3D projections are prepared and used for image interpretation. Evaluation of CT colonography datasets requires correct perception and interpretation of colonic lesions and filling defects. Various criteria are needed for correct interpretation of filling defects and differentiation between genuine lesions and artifacts. Such defects are characterized by their morphology, their structure, the absorption of contrast medium and their mobility. Knowledge of the morphologic and attenuation characteristics of common colonic lesions and of artifacts is essential for the correct interpretation of a filling defect. This review article summarizes the main imaging features of polyps, diverticula, lipomas, and carcinomas and also of common pseudolesions of the colon.

Size of surgical margin does not influence recurrence rates after curative liver resection for colorectal cancer liver metastases.

BACKGROUND: The aim of this study was to examine the relationship between surgical margin status and site of recurrence after potentially curative liver resection for colorectal metastases using an ultrasonic dissection technique. METHODS: Between January 2000 and December 2003, 176 patients underwent liver resection with curative intent for colorectal metastases at a single institution. Demographics, operative data, pathological margin status, site of recurrence and long-term survival data were collected prospectively and analysed. RESULTS: On pathological analysis, resection margins were positive in 43 patients, negative by 1-9 mm in 110, and clear by more than 9 mm in 23 patients. At a median follow-up of 33 months, 133 of 176 patients had developed a recurrence, only five of whom had recurrence at the surgical margin. Recurrence at the surgical margin was not significantly related to the size of the margin. Overall, the median time to recurrence was 12.6 months, which was independent of surgical margin size, although there was a significantly higher proportion of patients with multiple metastases in the group with a positive margin (P = 0.008). Margin status did not correlate significantly with either recurrence-free or overall survival. CONCLUSION: The rate of recurrence at the surgical margin was low and a positive margin was not associated with an increased risk of recurrence either at the surgical margin or elsewhere.

[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.