[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.

Predictive geometric factors in a standardized model of femoral neck fracture. Experimental study of cadaveric human femurs.

An experimental study was performed on 20 cadaveric human proximal femurs to investigate both the reproducibility of their mechanical behavior under uniaxial compression and the correlation of mechanical properties with geometric dimensions and bone density. These variables were assessed by radiography, physical measurement, and dual-energy X-ray absorptiometry (DEXA). The specimens were immobilized, loaded to the point of fracture, and analyzed with the help of a materials testing machine. The fractures invariably showed a similar pattern both in location (i.e. at the femoral neck) and in nature (i.e. "axial-shear" type according to the AO classification system). The mechanical properties of the tested proximal femurs correlated negatively with age (r = -0.39) and positively with sex (male femurs were stronger and correlated more closely than female femurs, P = 0.005). They showed a strong positive correlation with head diameter (r = 0.713, P = 0.0004), a moderate positive correlation with both neck axis length (r = 0.63) and neck diameter (r = 0.502), and a slight positive correlation with femoral neck-shaft angle (r = 0.326). All DEXA-based densitometry measures turned out to be powerful predictors of fracture force. The establishment of this solidly reproducible fracture model based on standardized loading conditions should have implications for future research on osteopenia/osteoporosis and preventive stabilization techniques.

[Pancreatic carcinoma: state of the art imaging]. / Pankreaskarzinom: State-of-the-Art-Imaging.

In view of the bad prognosis of pancreatic carcinoma the exact pre-surgical staging is essential for curative therapy. The rapid development of multi-detector computed tomography with the clinical implementation of 16 row scanners allow for almost isotropic pixel size and high-resolution multiplanar reconstruction. Sensitivity and specificity of magnetic resonance imaging are similar to those of computed tomography with lower values in the detection of vessel wall infiltration. Ultrasound may be a valuable modality for primary diagnosis.

Adrenal hemorrhage after orthotopic liver transplantation: MR appearance.

The purpose of this paper is to describe the MR imaging findings of right adrenal hemorrhage after orthotopic liver transplantation. Twenty-seven orthotopic liver transplantation patients underwent MR studies of the liver and/or biliary system. Patients were referred to MR examination because of suspected biliary complications ( n=22) or for evaluation of mass lesions ( n=5). The standard MR protocol included T1-weighted spin-echo (SE) or gradient-recalled echo (GRE) images and T2-weighted turbo SE (TSE) images with fat suppression. In addition, cholangiography pulse sequences and/or contrast-enhanced T1-weighted images were obtained according to specific indications. In 2 patients a right adrenal mass was detected at MR imaging. Three to 4 weeks after transplantation, the lesions were markedly hyperintense on T2-weighted images and showed a hypointense capsule. Follow-up MR examinations revealed a slight decrease in size and a change in morphology. Computed tomography examinations of these 2 patients, obtained 10 weeks after transplantation, showed resolution of the hemorrhage and transformation into a cystic lesion in one case and a complete resolution of the hemorrhage and a normal right adrenal gland in the other case. Adrenal hemorrhage after liver transplantation shows typical MR features and should not be mistaken for an adrenal tumor or a postoperative abscess.

Femoral neck fracture after removal of the standard gamma interlocking nail: a cadaveric study to determine factors influencing the biomechanical properties of the proximal femur.

We retrospectively analyzed 1334 patients who were implanted standard gamma interlocking nails (SGN) to stabilize trochanteric femoral fractures over the years 1992-1998. Reoperation to remove the nails was performed in 37 patients, in 9 of them purely because of pain. Three out of these 9 patients with removed SGN suffered femoral neck fractures in the early postoperative course after having been mobilized to full weight-bearing capacity. This complication was not observed with other implant systems and, considering the notoriously high complication rate of femoral neck fractures, severely reduces the value of the SGN concept per se. These findings in combination with other known shortcomings of SGNs prompted us to conduct an experimental study on the fracture force of excavated femurs addressing the hypothesis that the specific design of the SGN is responsible for the occurrence of fatigue fractures of the femoral neck. Eighteen matched pairs of fresh human cadaveric proximal femurs, which were treated by insertion and removal of (i) SGNs or (ii) dynamic hip screws (DHS) or (iii) by excavation in the absence of an implant, were subjected to incremental loading cycles and compared to the untreated contralateral femurs. Overall, the fracture force was found to be significantly lower among the treated than among the untreated bones. However, the fracture force required after removal of the DHS system was still significantly higher than for SGN or excavation alone. In this way, our findings demonstrate that removing relatively big implants such as SGN can cause serious complications such as femoral neck fractures. We therefore recommend to leave this type of device in place even after fracture healing except in cases of deep and chronic infection.

MRI in the diagnosis of a peritoneal leak in continuous ambulatory peritoneal dialysis.

Mechanical problems in continuous ambulatory peritoneal dialysis (CAPD) can result in ultrafiltration failure and disruption of CAPD therapy. The recently described tool of CT peritoneography with water-soluble contrast medium has the disadvantage of radiation and instillation of nephrotoxic substances. We report a child with a peritoneal leak diagnosed by MRI after instillation of a gadodiamide-dialysate mixture. This method provided good anatomical detail without radiation or nephrotoxic agents.

Displacement of coils into the lung during embolotherapy: clinical importance and follow-up with helical CT.

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate the clinical importance and computed tomographic (CT) appearance of coils displaced into the lung during embolotherapy. MATERIALS AND METHODS: The authors retrospectively studied clinical charts and serial chest images from 25 consecutive patients after coil embolization. Chest radiography was performed in all patients, whereas helical chest CT was performed only in patients in whom dislocated coils were visible on chest radiographs. Coils were applied for the treatment of peripheral arteriovenous (AV) malformations and fistulas (n = 9), renal AV malformations or fistulas (n = 8), and primary or secondary tumors (n = 8). Clinical charts were analyzed for short- and long-term symptoms; chest radiographs and CT scans were reviewed for signs indicative of pulmonary infarction. RESULTS: None of the patients had clinical symptoms suggestive of pulmonary infarction. In two of the 25 patients (8%), displaced coils were seen in the pulmonary vasculature at chest radiography; these patients had been treated for renal AV fistula and peripheral AV fistula, respectively. One patient had two coils in the left hemithorax (upper and lower lobe), and the other patient had two coils in the right hemithorax (middle lobe). Neither of the patients had abnormalities suggestive of pulmonary infarction at helical CT. CONCLUSION: Chest radiography can help confirm the presence of coils displaced to the pulmonary vasculature during embolotherapy. Helical CT can also help rule out the presence of coil-associated pulmonary infarction.

Inadvertent transpericardial insertion of a central venous line with cardiac tamponade failure of preventive practices.

A 56-year-old man who had undergone cardiac surgery suffered from cardiac tamponade after administration of contrast-medium through a central venous catheter. Pericardiotomy showed the catheter transversing the pericardial sac just beneath an unusual high reflection and then reentering the superior vena cava. Preventive practices including chest radiography, confirming free venous blood return and manometry may fail to detect catheter malposition in rare cases. Knowledge of potential pitfalls in using generally recommended safety practices and continuous vigilance are essential for the anesthesiologist and intensivist in avoiding potentially lethal hazards.

Measurement of hepatic perfusion with dynamic computed tomography: assessment of normal values and comparison of two methods to compensate for motion artifacts.

RATIONALE AND OBJECTIVES: To assess normal values of hepatic perfusion by dynamic, single-section computed tomography, to compare two methods of data processing (a smoothing with a fitting procedure), and to evaluate the influence of motion artifacts. METHODS: Twenty-five volunteers with no history or suspicion of liver disease were examined (age range, 32.8-81.1 years). All examinations were subjectively ranked into groups 1 through 3 according to the degree of motion artifacts (negligible, moderate, severe). All data were processed with a smoothing procedure and a pharmacokinetic fitting procedure (TopFit). The arterial, portal venous, and total hepatic perfusion; the hepatic perfusion index (HPI); and the arterial/portal venous ratio (A/P ratio) were calculated with both procedures. RESULTS: Mean hepatic perfusion, as assessed with the fitting procedure and the smoothing procedure, respectively, was as follows: arterial, 0.20 and 0.22 mL x min(-1) x mL(-1); portal venous, 1.02 and 1.24 mL x min(-1) x mL(-1); total perfusion, 1.22 and 1.47 mL x min(-1) x mL(-1); HPI, 16.4% and 15.4%; and A/P ratio, 0.20 and 0.19. The differences were significant for the portal venous and total hepatic perfusion. The portal venous and total hepatic perfusion values showed significant differences between group 1 and groups 2 and 3 for both procedures. HPI and the A/P ratio showed no significant differences at all. CONCLUSIONS: Motion artifacts and the type of data processing influence the assessment of the arterial, portal venous, and total hepatic perfusion but do not influence measurement of the HPI and the A/P ratio.

Timing of the hepatic arterial phase during contrast-enhanced computed tomography of the liver: assessment of normal values in 25 volunteers.

OBJECTIVES: To define normal values of the beginning and duration of the hepatic arterial phase (HAP) during contrast-enhanced computed tomography (CT). METHODS: Twenty-five volunteers (16 men, 9 women; mean age, 60.0 years) without history or suspicion of liver disease were examined with dynamic single-section CT. Scanning was performed at a single level that included the liver, aorta, and portal vein. A series of 25 scans was obtained over a period of 88 seconds (1 baseline scan followed by 16 scans every 2 seconds and 8 scans every 7 seconds) beginning with the injection of a bolus of contrast agent (40 mL, 10 mL/s) and a 40-mL NaCl bolus chaser. Contrast enhancement in the liver, aorta, and portal vein was measured with regions of interest, and time-density curves were obtained. These data were processed with a pharmacodynamic fitting program and the duration of the HAP was calculated. The onsets of the HAP and the portal venous phase were assessed as lag times, referring to the beginning of enhancement in the abdominal aorta. RESULTS: The mean lag time of the HAP was 5.4 seconds after the aorta and the mean duration was 8.6 seconds. The mean lag time of the portal venous phase was 13.9 seconds after the aorta. CONCLUSIONS: These data can be used to optimize protocols for routine CT. Because of the short duration of the HAP, imaging of the entire liver during this phase is possible only with multidetector CT scanners.

Preoperative fast MRI of brain tumors using three-dimensional segmented echo planar imaging compared to three-dimensional gradient echo technique.

The purpose of this study was to compare the diagnostic efficacy of a newly developed T(1)-weighted three-dimensional segmented echo planar imaging (3D EPI) sequence versus a conventional T(1)-weighted three dimensional spoiled gradient echo (3D GRE) sequence in the evaluation of brain tumors. Forty-four patients with cerebral tumors and infections were examined on a 1.0 T MR unit with 23 mT/m gradient strength. The total scan time for the T(1) 3D EPI sequence was 2 min 12 s, and for a conventional 3D GRE sequence it was 4 min 59 s. Both sequences were performed after administration of a contrast agent. The images were analyzed by three radiologists. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, and image artifacts. In addition, signal-to-noise and contrast-to-noise-ratio (C/N) were calculated. The gray-white differentiation and C/N ratio of 3D EPI were found to be inferior to conventional 3D GRE images, but the difference was not statistically significant. In the qualitative comparison, lesion detection and conspicuity of 3D EPI images and conventional 3D GRE images were similar, but a tow-fold reduction of the scanning time was obtained. With the 3D EPI technique, a 50% scan time reduction could be achieved with acceptable image quality compared to conventional 3D GRE. Thus, the 3D EPI technique could replace conventional 3D GRE in the preoperative imaging of brain.

Detection of focal hepatic lesions: comparison of unenhanced and SHU 555 A-enhanced MR imaging versus biphasic helical CTAP.

The purpose of this study was to compare the diagnostic sensitivity of unenhanced magnetic resonance (MR) imaging, and MR imaging with a new superparamagnetic iron oxide (SPIO)-enhanced contrast agent (SHU 555 A) with biphasic helical computed tomography during arterial portography (CTAP) in patients with focal liver lesions. Eighteen patients with a total of 91 (78 malignant, 13 benign) proven liver lesions underwent unenhanced short tau inversion recovery (STIR), T2-weighted (T2-w) TSE, and SHU 555 A-enhanced T2-w turbo spin-echo (TSE) MR imaging and biphasic helical CTAP. The standard of reference was histopathologic analysis of resected specimens in 59 lesions, intraoperative ultrasound with biopsy in 20 lesions, and CT-guided biopsy and follow-up in 12 lesions. Diagnostic performance of the imaging modalities was compared quantitatively and qualitatively by assessing lesion involvement in liver segments. There were 68 lesions detected on unenhanced T2-w TSE, which resulted in a sensitivity of 75%. With the STIR sequence, 76 lesions were detected, for a sensitivity of 84%, and with SHU 555 A-enhanced MRI, 84 lesions were detected, for a sensitivity of 92%. CTAP detected 88 lesions, for a sensitivity of 97%. The accuracy for unenhanced T2-w TSE was 98%, for STIR 99%, for enhanced-MRI 100%, and for CTAP 95%. The specificity was 100% for SHU 555 A-enhanced MRI and 95% for CTAP. SHU 555 A-enhanced MRI was superior to nonenhanced MRI (P < 0.05) and equivalent to CTAP in terms of sensitivity. Due to the absence of false-positive results on SHU 555 A-enhanced MRI, the specificity and accuracy of enhanced MRI were higher than those of CTAP, but the difference was not statistically significant (P = 0.134).

Ultrafast magnetic resonance imaging of the brain.

The purpose of this study was to compare the diagnostic efficacy of single shot fast spin echo sequence (SSh-FSE), and single shot GRASE-sequence (SSh-GRASE) to the conventional T(2)-weighted fast spin echo-sequence (T(2)-FSE) in the imaging of brain disorders. Thirty three patients with high signal intensity lesions on T(2)-weighted images (n = 28), or intracerebral hemorrhage (n = 5), were examined on a 1.0 T MR scanner, with 23 mT/m gradient strength. The scan time for the conventional T(2)-FSE-sequence was 2 min 57 s, the scan time for the single shot-FSE-, and single shot-GRASE-sequences was 11 sec, and 17 sec, respectively. Twenty-one patients remained still during the examination, whereas 12 could not stay still with consecutive marked motion artifacts. Images were reviewed by three radiologists. Lesion conspicuity, image quality, and artifacts were scored on a subjective scale. Signal-to-noise ratios of lesions and normal tissue and contrast-to-noise ratios (CNR) were measured by region of interest (ROI). In the patient group without motion artifacts conspicuity for lesions > or =5 mm did not show a significant difference on conventional T(2)-FSE, single shot-FSE and single shot-GRASE. Detectability of the smaller lesions was significantly inferior on single shot-FSE-, and single shot-GRASE-sequences in artifact free images. For the patient group with motion artifacts SSh-FSE and SSh-GRASE were markedly superior to the conventional T(2)-FSE. Grey-white differentiation was better on conventional T(2)-FSE. Physiologic ferritin as well as pathologic hemosiderin depositions were slightly darker and therefore better visible on SSh-GRASE than on SSh-FSE. Conventional T(2)-FSE showed significantly more artifacts. In conclusion, SSh-FSE and SSh-GRASE imaging can be used for rapid imaging of the brain in those patients who are claustrophobic or in patients with involuntary movements due to extrapyramidal disorders, as well as in children in whom anesthesia is contraindicated or sedation is not possible.

Complications of continuous ambulatory peritoneal dialysis: findings on MR peritoneography.

OBJECTIVE: The purpose of this study was to assess the diagnostic value of MR peritoneography in complications of continuous ambulatory peritoneal dialysis. SUBJECTS AND METHODS: Twenty consecutive patients treated with continuous ambulatory peritoneal dialysis who were clinically suspected of dialysis-related complications were prospectively studied with MR peritoneography. For MR peritoneography, 20 ml of gadodiamide was added to 2000-ml dialysate solution (1.36% glucose) that was instilled into the peritoneal cavity. MR peritoneography was performed with the peritoneal cavity filled (n = 12) and after complete drainage of the contrast material-dialysate mixture (n = 20) on a 1.5-T MR unit with a phased array coil. Imaging included axial T1-weighted fast low-angle shot (TR/TE, 174/4.2) with and without fat saturation and axial and coronal T2-weighted fat-saturated turbo spin-echo (3000/138) sequences. All studies were performed without IV contrast material. Images were reviewed for evidence of peritoneal leaks, hernias, loculated fluid collections, and adhesions. RESULTS: Abnormal findings were detected in 13 (65%) of 20 patients and included retroperitoneal leaks (n = 6), diaphragmatic leaks (n = 2), catheter exit-site leaks (n = 2), inguinal hernias (n = 2), and peritoneal adhesions (n = 1). CONCLUSION: MR peritoneography is useful for the evaluation of complications related to continuous ambulatory peritoneal dialysis, and it offers excellent tissue contrast and multiplanar imaging for assessment of complications.

Helical and conventional CT in the imaging of metallic foreign bodies in the orbit.

PURPOSE: To compare helical CT to conventional CT imaging in the assessment of orbital metallic foreign bodies with regard to image quality, scanning time, and radiation exposure. METHODS: Twenty-four standardized metallic foreign bodies, placed into the orbit (anterior, epibulbar, posterior) of cadaver heads were studied. Helical CT scanning in the axial plane with multiplanar reconstruction of coronal and sagittal images was performed as well as conventional CT imaging with direct scanning in the axial and the coronal planes (Tomoscan SR 7000, Philips, The Netherlands). Two masked observers consensually graded the studies using 5 predetermined criteria. Radiation dose delivered to the lens and scanning time were measured for the helical and the conventional CT imaging workup. RESULTS: Helical CT imaging scored statistically significantly better with regard to overall accuracy of foreign body localization and presence of beam-hardening streak artifacts from dental fillings. Conventional CT scored significantly better with regard to stair-step artifacts. The radiation dose delivered to the lens was 35.4 mGy for helical CT imaging and 73.9 mGy for conventional CT workup (axial and coronal scanning). Total scanning time was 18 seconds for helical CT axial scanning and 104 seconds for conventional CT axial and coronal scanning. CONCLUSION: Helical CT is superior to conventional CT imaging, because it can provide adequate information about orbital metallic foreign bodies with a single acquisition, thus reducing both the number of examinations and the radiation exposure for the patient.

Dolichoodontoid. A rare cranio-cervical anomaly--MRI findings.

The case of a 40-year-old woman with a dolichoodontoid, a rare congenital anomaly of the cranio-cervical region, is presented. Due to summation image and overlying bony structures, plain radiographs in two planes were inconclusive. MRI revealed the hyperplasia of the odontoid process, allowed a grading of the subtype of this disorder and demonstrated its relationship to the neural structures within the foramen magnum and the upper cervical spine. Additional inflammatory disease, suspected in this patient with long standing rheumatoid arthritis could be excluded by MRI.

Orbital helical computed tomography in the diagnosis and management of eye trauma.

OBJECTIVE: To prospectively determine the accuracy of helical computed tomography (CT) and multiplanar reconstruction and its value in surgical planning for the management of ocular trauma with suspected intraocular and orbital foreign bodies using surgical and clinical follow-up findings as the gold standard. DESIGN: Prospective, observational case series. PARTICIPANTS: Thirty-six patients with ocular trauma and suspected foreign bodies were studied. INTERVENTION: All patients were examined using a standardized scanning protocol with helical CT direct scanning in the axial plane and multiplanar reconstruction of coronal and sagittal planes. MAIN OUTCOME MEASURES: The images were analyzed for the presence and number of intraocular and orbital foreign bodies, anatomic location, and foreign body size. The surgical and clinical follow-up findings (contact lens examination, gonioscopy, indirect ophthalmoscopy and scleral depression, perimetry, color testing, measurement of size) were used as the gold standard to which the image results were compared. RESULTS: Helical CT showed a single intraocular foreign body in 14 patients, a single orbital foreign body in 9 patients, and multiple orbital foreign bodies in 2 patients. Intraocular or orbital foreign bodies were excluded in 11 patients. Twenty foreign bodies were correlated with surgical results. Surgical and clinical follow-up findings were in agreement with helical CT results regarding the detection and determination of the number of presumed foreign bodies. Localization to intraocular versus orbital compartment and proximity to the optic nerve was accurate in all patients. Determination of size of the foreign bodies on the helical CT images was reliable and repeatable. CONCLUSIONS: Helical CT axial scanning with multiplanar reconstruction is accurate at detecting and localizing intraocular and orbital metallic, glass, and stone foreign bodies. This imaging method aids the surgeon in choosing the surgical approach to retained intraocular and orbital foreign bodies.

[Radiologic staging of thoracic and abdominal tumors in childhood]. / Radiologisches Staging von thorakalen und abdominalen Tumoren im Kindesalter.

Thoracoabdominal tumors in childhood can arise from all organs and affect children from the neonate to the adolescent. Better prognosis of childhood tumors, due to better biological understanding and improvement of chemotherapy, require sufficient radiological staging. Sufficiency in radiological staging needs modern cross-sectional techniques with high resolution, good availability and lower radiation dose. In general computed tomography (CT) is being used for radiological staging; increasingly MR imaging is being used because of multiplanar imaging techniques. Replacement of invasive techniques such as myelography and lymphography and modern cross-sectional techniques create painless staging conditions. Nevertheless, scintigraphy will always be a major examination technique, especially for evaluation of metastases and postoperative control examinations. The most common thoracoabdominal tumors in childhood and their staging are described.

[Staging of carcinomas of the upper gastrointestinal tract. The current status of diagnostic imaging]. / Staging von Karzinomen des oberen Gastrointestinaltraktes. Standortbestimmung der Bildgebung.

Esophageal carcinoma: CT and endosonography are complementary and the most important imaging modalities at present for staging. After endoscopic and histological diagnosis, CT of the thorax and the abdomen is used. With the proof of local infiltration of a neighbouring organ or in the presence of distant metastasis, palliative therapy can be started. If CT is not conclusive or no local infiltration or distant metastasis is proven, endosonography should be performed. Gastric carcinoma: At present endosonography shows the highest accuracy for diagnosis of the T stage. For differentiation between T3 and T4 tumors the accuracy of CT is not sufficient to predict resectability. The N stage can be determined at present by no modality with sufficient accuracy. Distant metastasis can be diagnosed by CT with high sensitivity and specificity. Small bowel carcinoma: These rare tumors are diagnosed with high accuracy by enteroclysis, whereby the diagnosis takes place at a late stage due to the nonspecific clinical findings.

Pseudoaneurysm of the internal carotid artery after shrapnel injury in World War II: demonstration by CT angiography with 3D MIP reconstruction.

A case of pseudoaneurysm of the left internal carotid artery (ICA) after shrapnel injury is demonstrated by intra-arterial digital subtraction angiography (DSA) and computed tomography angiography (CTA) with subtraction technique. Although the pseudoaneurysm was well demonstrated by intra-arterial DSA, CTA was the only modality to demonstrate the three-dimensional shape of the perfused part of pseudoaneurysm and the aneurysmal neck, which affected the therapeutic strategy. The CTA technique is useful in the assessment of large pseudoaneurysms and for therapeutic planning.