Echography in the study of adenopathies of the upper abdomen

Four-hundred eighty-five patients underwent US examination; 183 of them had gastric cancer, 239 colorectal cancer, 38 pancreatic cancer, 11 esophageal cancer, and 14 had gastric lymphoma. All patients underwent surgery. In 95 cases fine-needle biopsy under US guidance was performed. Lymphadenopathies were classified by the criteria proposed by Yoshinaka et al., type I: poorly-defined borders, diffuse internal echoes; type II: well-defined borders, diffuse internal echoes; type III: well-defined borders, notchings, strong internal echoes. Twenty/twenty-nine type I, 66/98 type II, and 39/43 type III adenopathies were found to be neoplasm-positive. Of 73 patients with adenopathy from gastric cancer, 9 were type I, 42 were type II, and 22 were type III (183 patients examined); of 9 patients with adenopathy from esophageal cancer, 7 were type II and 2 were type III (11 patients examined); of 48 patients with adenopathy from colorectal cancer, 5 were type I, 28 were type II, and 15 were type III (239 patients examined); of 29 patients with adenopathy from pancreatic cancer, 7 were type I, 18 were type II, and 4 were type III (38 patients examined); finally, of 11 patients with adenopathy from gastric lymphoma, 8 were type I, and 3 were type II (14 patients examined). The relationship between US and pathology was possible from a statistical point of view only. Type I lymphadenopathies seem to suggest lymphomatous involvement, whereas type III ones suggest metastatic involvement. US is a valid approach method, which must be supported by other investigation techniques--e.g., CT and lymphography--in order to avoid high false-negative percentages.     

Fat-saturation MR imaging of the upper abdomen

The fat-saturation (fatsat) MR technique decreases the signal intensity of fat, thereby enhancing the definition of upper abdominal organs and reducing artifacts while maintaining the T1 and T2 information available on spin-echo sequences. To evaluate the potential of fatsat in examining the abdomen, we conducted a prospective study involving 30 subjects, including four normal volunteers, 18 patients investigated for liver disease, and eight patients studied for miscellaneous abdominal disease. Short TR, 300-600/15-20 (TR/TE), and long TR, 2000-2500/20-30, 70-80, spin-echo images with and without fatsat were compared. The images were evaluated both qualitatively and quantitatively. Qualitative assessment was made with receiver-operating-characteristic (ROC) curve analysis of the confidence level of observers to detect the presence of disease, comparing fatsat with standard spin-echo sequences. ROC analysis showed greater interpreter confidence and accuracy for fatsat sequences than for standard spin-echo sequences. The measured signal-difference-to-noise (SD/N) ratio comparing upper abdominal organs with surrounding tissue revealed the highest values for short TR/TE regular spin echo, followed by short TR/TE fatsat. The highest SD/N ratio for hepatic masses was with long TR/TE fatsat followed by short TR/TE fatsat. The results of this study suggest that the fatsat technique may improve abdominal MR imaging.     

Streak artifacts in dynamic CT. A phantom study of the anterior upper abdomen

Experiments with a body phantom during dynamic CT scanning with the Somatom 2 CT scanner indicate that the periodic streak artifacts seen on the anterior part of the liver in patients are caused by peristalsis of the stomach and resulting motion of the air fluid level. Therefore, the attenuation values of the anterior portion of the liver artifactually oscillate around the baseline value during the dynamic series of scans. This artifact is produced by a change in the position of the stomach air fluid level and is dependent on the direction of tube rotation. The mean of the artifactually oscillating attenuation readings is close to the mean density but usually useless in dynamic CT because the attenuation values change so rapidly in the dynamic phase that averaging measurements also will cause errors.     

Fungal lesions of the organs of the upper abdomen]

The authors report on 14 cases of fungal parenchymal infections of the abdomen detected with CT and/or US in immunodepressed patients. Image patterns and the capabilities of the two diagnostic techniques are analyzed in the early detection of fungal lesions. CT was the first-choice examination, followed by US, in 9 patients; laboratory tests followed in 3 cases; US was performed first (and CT second) in 1 patient; finally, US alone was performed in 1 patient. The information yielded by CT and that given by US overlapped in 8/9 cases: in the extant patient, US demonstrated multiple fungal microabscesses of liver, while CT was negative, probably due to low liver density. CT patterns were multiple, small and round nonenhanced areas. Since the indiscriminate administration of intravenous contrast medium is unsuitable, CT cannot be performed first. On the other hand, in several patients liver CT with no contrast medium gave the same results for venous and fungal lesions. Compared with CT, US is a safer technique which is easier to perform and to evaluate. Therefore, US should be the exam of choice in immunodepressed patients with suspected fungal lesions. US is likely to demonstrate, in most cases, a pathologic condition (fungal microabscesses) as well as vascular and biliary anatomy.     

US of the upper abdomen: factors influencing image quality

A controlled blind study of 226 patients was performed to determine the advantages of fasting prior to upper abdominal ultrasonography (US) as well as the influence of other factors on image quality. The ratio of weight to height (a reflection of body build) was found to most often correlate negatively with image quality for all organs, followed by age for the biliary tract, pancreas, and kidneys and sex (in males) for the pancreas. Only the biliary tract was shown slightly better as the result of fasting. Images obtained during the afternoon tended to be somewhat better. The authors conclude that upper abdominal US can be performed at any time in patients who have not fasted, as it is primarily other factors that determine image quality. Only if evaluation of the biliary tract is inconclusive need the patient be reexamined after fasting.     

A prospective study comparing different iodine concentrations for triphasic multidetector row CT of the upper abdomen

OBJECTIVES: To investigate the effect of different iodine concentrations at either constant injection or iodine administration rates but constant total iodine load on contrast enhancement of liver, pancreas and spleen by multidetector row CT. MATERIALS AND METHODS: One hundred and twenty consecutive patients (70+/-6 years) underwent triphasic liver CT at a four-channel multidetector-row CT using the non-ionic contrast medium iopromide. Patients were divided into six equal groups-I: 150 ml, 240 mg/ml at 4 ml/s; II: 120 ml, 300 mg/ml at 4 ml/s; III: 97.3 ml, 370 mg/ml at 4 ml/s; IV: 150 ml, 240 mg/ml at 5 ml/s; V: 120 ml, 300 mg/ml, 60 ml at 6 ml/s, 60 ml at 3 ml/s; VI: 97.3 ml, 370 mg/ml at 3.3 ml/s. ROIs were measured in the liver, the pancreas, and the spleen in unenhanced, arterial, portal venous, and equilibrium phase. RESULTS: At a constant injection rate of 4 ml/s, pancreatic enhancement over baseline only in the arterial phase was significantly higher at 370 mg/ml (58+/-15 HU versus 59+/-18 HU versus 74+/-20 HU for groups I-III, respectively (p<0.02)). Comparison of different iodine concentrations at constant iodine administration rate (groups II, IV and VI) and of all six protocols revealed no significant differences at either phase. CONCLUSIONS: At a constant iodine load and constant injection rates, the high-iodinated contrast agent iopromide at 370 mg/ml improves pancreatic enhancement in the arterial phase. At constant iodine load and constant iodine administration rates, there is no significant effect of different iodine concentrations.     

Acoustic prism causing sonographic duplication artifact in the upper abdomen

A variable prism of fat frequently occurs in the anterior abdominal wall that can produce confusing double-image artifacts on sonograms. This artifact is seen most frequently in the pelvis but is also seen in the upper abdomen, and is related to anatomic variations and the size of some ultrasound transducers. Phantom studies and a review of the CT scans of 100 patients were used to document the anatomy and frequency of occurrence of this variant.     

Clinical application of helical scanning CT of upper abdomen

The helical scanning CT unit, in which an X-ray tube continuously rotates at the rate of one revolution per second with constant movement of the table on which the patient is placed, was clinically tested in scanning of upper abdomen. Quality of the images obtained was equal to that of conventional CT. The images were particularly good at an X-ray beam width of 5 mm and table movement of 5 mm/sec with scan parameters of 120 kvp, 200 mA. Because of limitation of the X-ray tube capacity. X-ray beam width of 5 mm and table movement of 10 mm/sec with scan parameters of 120 kvp, 150 m, would be the most appropriate clinically. Application of the helical scanning CT will result in examination times shorter than in the case of conventional high-resolution CT and be obtained images at early vascular enhancement phase through the whole scanning area, so that it can be expected to be extremely useful in clinical diagnosis involving upper abdomen.     

Optimization of the technic in the study of the upper abdomen using magnetic resonance. I. Artifact reduction

Complete motion artifact suppression is possible in abdominal MR imaging with the simple optimization of sequence parameters, with no need for special softwares. The authors have studied the influence of sequence parameters modification on the signal/noise relation and on the presence of motion artifacts. The tested parameters included Repetition Time (TR), 150 to 2000 ms, Echo Time (TE), 20 to 120 ms, and the number of acquisitions, 2 to 16. In T1-weighted sequences, the major advantages were offered by the short TR and short TE association, with many acquisitions. Optimal signal/noise relation and complete motion artifact suppression were thus obtained. In T2-weighted sequences, TE values had to be changed according to the desired contrast enhancement, and the number of acquisitions could not be increased to more than 2 in order to keep the acquisition time short.     

Time-resolved MR angiography of the upper abdomen: initial clinical experience

In this study, thirty-eight patients with a variety of upper abdominal diseases were examined with three-dimensional time-resolved MR angiography (7 sec/data set). Visualisation of arterial and venous anatomy was excellent in the majority of patients. Moreover, subtraction images could be calculated and organ perfusion could be assessed. It is concluded that this technique opens new perspectives for a comprehensive evaluation of vascular and parenchymal disease. Received: 14 April 1998; Revision received: 23 October 1998; Accepted: 9 November 1998