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Biomedical subjects

P Soyer

Publications and source records attributed to P Soyer.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Dynamic gadolinium-DOTA-enhanced MR imaging at 1.0 T. Value in the differentiation of hepatic tumors.

A prospective study was performed to determine the value of dynamic gadolinium-tetraazacyclododecane-tetraacetic acid (Gd-DOTA)-enhanced magnetic resonance (MR) imaging at 1.0 T, using a gradient-echo (GRE) technique, in the differentiation of hepatic tumors. Fifty patients with hemangiomas (n = 14), focal nodular hyperplasia (n = 4), and malignant tumors of the liver (n = 32) underwent GRE MR imaging at 1.0 T before and repeatedly for 4 minutes after intravenous bolus administration of Gd-DOTA. The diagnoses were proved by histology or follow-up examination. On unenhanced GRE images, hemangiomas had a significantly lower tumor-to-liver contrast-to-noise (C/N) ratio (-14.74 +/- 4.49) than did the other tumors (-6.96 +/- 5.49) (p < 0.02), and benign tumors had a significantly lower C/N ratio (-12.43 +/- 5.99) than did malignant tumors (-7.29 +/- 5.71) (p < 0.05). On contrast-enhanced images, hemangiomas had a significantly lower C/N ratio (-17.60 +/- 6.90) than did the other tumors (-5.07 +/- 12.12) (p < 0.05) in the early phase. During the delayed phase, hemangiomas had a significantly higher C/N ratio (3.90 +/- 3.81) than did the other tumors (-4.85 +/- 6.51) (p < 0.01), and benign tumors had a significantly higher C/N ratio (3.21 +/- 3.65) than did malignant tumors (-5.56 +/- 6.56) (p < 0.001). Our data suggest that dynamic Gd-DOTA-enhanced MR imaging at 1.0 T provides useful information to differentiate between benign and malignant hepatic tumors, and to distinguish hemangiomas from the other tumors.

Adult↗
PubMedDate not supplied

Capsular retraction of the liver in malignant tumor of the biliary tract MRI findings.

Retraction of the liver capsule adjacent to a hepatic tumor is an unusual feature that has received little attention in radiological literature. We report two patients with pathologically proved malignant tumor of the biliary tract (one cholangiocarcinoma and one gallbladder cancer) in whom magnetic resonance imaging (MRI) showed retraction of the liver capsule adjacent to the tumors. MRI was performed at 1.0 T, using a spin-echo (SE) technique, with T1 (TR/TE = 450/15 msec) and T2 (TR/TE = 2000/45 to 90 msec)-weighted images. Capsular retraction was seen on both T1- and T2-weighted SE MRI. Although capsular retraction of the liver adjacent to hepatic tumors is highly suggestive for epithelioid hemangioendothelioma, these two cases confirm that retraction of the liver capsule adjacent to hepatic tumors can be associated with other types of tumor, and especially with malignant tumors of the biliary tract.

Bile Duct Neoplasms↗
PubMedDate not supplied

Primary leiomyosarcoma of the liver MR findings.

The magnetic resonance (MR) features of a 67-year-old woman with a surgically and pathologically proved primary leiomyosarcoma of the liver studied at 1.0 T, using T1- (TR/TE = 450/15), and T2- weighted (TR/TE = 2200/45 to 90) spin-echo (SE) images, are described. On T1-weighted SE images, the tumor was well defined, was slightly heterogeneous, and displayed hypointensity to the adjacent hepatic parenchyma, with an area displaying hyperintensity. On T2-weighted SE images, the tumor was encapsulated, was heterogeneous, and displayed marked hyperintensity.

Aged↗
PubMedDate not supplied

[Percutaneous drainage of abdomino-pelvic collections. Indications, techniques, and results].

Extra-parenchymal collections in the abdomen and pelvis are a not infrequent occurrence in gastrointestinal pathologies. Twenty years of experience have proved percutaneous drainage to be a safe and effective therapeutic modality. Several studies have demonstrated the efficacy of radio-guided percutaneous drainage which can serve as a substitute for open surgical drainage in 70% of cases. This therapeutic modality should be considered for every case of abdomino-pelvic collection.

Abdominal Abscess↗
PubMedDate not supplied

Differentiation between hepatic cavernous hemangioma and malignant tumor with T2-weighted MRI: comparison of fast spin-echo and breathhold fast spin-echo pulse sequences.

PURPOSE: The goal of our study was to compare a T2-weighted breathhold fast spin-echo (BHFSE) technique with T2-weighted nonbreathhold fast spin-echo (FSE) technique for characterizing cavernous hemangioma of the liver and differentiating this entity from malignant tumor. MATERIALS AND METHODS: Eighteen patients with cavernous hemangiomas and 18 patients with malignant hepatic tumors were studied with T2-weighted MRI with a nonbreathhold FSE technique with and without fat suppression and with a BHFSE technique without fat suppression. Hepatic lesions were analyzed quantitatively using signal intensity (SI) and contrast-to-noise (C/N) ratio. In addition, images were qualitatively compared for accuracy in characterizing hepatic lesion. RESULTS: Quantitatively, hemangioma had significantly higher SI and C/N ratios than did the malignant tumor on every pulse sequence (P < 0.01). Qualitatively, all malignant tumors were correctly categorized; differentiation between cavernous hemangioma and malignant tumor was impossible in three cases of cavernous hemangioma with the three pulse sequences (92% accuracy, 100% sensitivity, and 83% specificity). CONCLUSION: T2-weighted FSE and BHFSE MRI shows comparable levels of accuracy for differentiating between hepatic cavernous hemangioma and malignant tumor. Because overlap may exist using quantitative measurement, morphologic patterns must be carefully analyzed, supporting that quantitative analysis and morphologic evaluation are complementary.

Adult↗
PubMedDate not supplied

CT of fibrolamellar hepatocellular carcinoma.

We retrospectively evaluated 10 patients with pathologically proven fibrolamellar hepatocellular carcinoma (FLHCC) to assess the utility of CT (n = 9), ultrasound (n = 10), angiography (n = 9), and MR (n = 3). The tumors were solitary in 6 of 10 patients, well delineated in 7 of 10, and hypervascular in 8 of 10. With use of multimodality imaging techniques, a central scar was demonstrated in 3 of 10 patients, calcifications in 4 of 10, dilated intrahepatic ducts in 2 of 10, thrombosis of a segmental portal branch in 2 of 10, and lymph node involvement in 3 of 10. Computed tomography was the most accurate technique for diagnosis and staging. Magnetic resonance imaging helped establish the correct diagnosis in one patient. This report emphasizes the wide variability of imaging features of FLHCC and the predominant role of CT for suggesting the diagnosis.

Adolescent↗
PubMedDate not supplied

MRI of liver metastases from colorectal cancer vs. CT during arterial portography.

A prospective study was performed to compare, with a lesion-by-lesion analysis, the sensitivities of high field strength MRI and CT during arterial portography (CTAP) in detecting hepatic metastases from colorectal cancer. Twenty-one patients with liver metastases from colorectal cancer were prospectively investigated by high field strength MRI (1.5 or 2 T) and CTAP. High field strength MRI was performed with pre and post gadopentetate dimeglumine enhanced T1-weighted SE sequences and T2-weighted SE sequences. All patients underwent partial hepatectomy and 37 metastases were surgically and pathologically proved. The metastasis detection rate (sensitivity) was 94% (35 of 37) for CTAP and 78% (29 of 37) for high field strength MRI. The 16% (95% confidence interval: 1-31%) difference in sensitivity between CTAP and high field strength MRI was statistically significant (p < 0.05, McNemar test). The use of gadopentetate dimeglumine did not improve the sensitivity of T1-weighted SE sequences. Since our study demonstrated significant difference in sensitivities between high field strength MRI and CTAP in our group of patients, we can conclude that high field strength MRI cannot replace CTAP in the preoperative evaluation of patients with liver metastases from colorectal cancer. Computed tomography during arterial portography must be considered as the preoperative gold standard.

Colonic Neoplasms↗
PubMedDate not supplied

MRI of adenomatous hyperplastic nodules of the liver in Budd-Chiari syndrome.

We present two cases of adenomatous hyperplastic nodules (AHN) occurring in patients with chronic Budd-Chiari syndrome who were investigated with MRI. In one case the foci of AHN were isointense to the liver on spin echo (SE) T1-weighted MRI and were hyperintense on both SE proton density and SE T2-weighted MRI. In the other case the nodules were hyper-intense on SE T1-weighted MRI. They were isointense on SE proton density-weighted MRI and became slightly hyperintense on SE T2-weighted MRI. Furthermore, in both cases one nodule displayed hyperintensity with hypointense rims on SE T2-weighted MRI.

Adult↗
PubMedDate not supplied

Dynamic CT in pancreatic lymphoma.

We retrospectively reviewed the dynamic CT examinations of eight patients with pancreatic lymphoma. Four tumors were rounded masses with well-defined contours, four were more infiltrating lesions. The median cross-sectional diameter of the tumors was 6 cm (range 2.5-12 cm). At dynamic CT, the tumors were hypodense (n = 8) and somewhat heterogeneous (n = 6). Additional features were enlarged lymph nodes, 1-3 cm in diameter (n = 5), dilatation of the biliary tract and pancreatic duct (n = 5), abnormalities in the fat around the celiac trunk and/or the superior mesenteric artery (n = 4), and venous stenosis or occlusion (n = 7). The CT findings of pancreatic lymphoma are more various than has been previously reported. Findings such as small tumor size, well-defined contours, tumor heterogeneity, pancreatic duct dilatation, and venous invasion may be seen. Pancreatic lymphoma cannot be reliably distinguished from pancreatic carcinoma by CT findings alone.

Adipose Tissue↗
PubMedDate not supplied

Cystic tumors of the pancreas: dynamic CT studies.

OBJECTIVE: Our retrospective study was performed to reassess the common dynamic CT manifestations of cystic tumors of the pancreas and to determine whether they might allow the differentiation between benign and malignant tumors. MATERIALS AND METHODS: Dynamic CT examinations of 19 patients with 20 cystic tumors of the pancreas, including 7 serous cystadenomas, 3 benign mucinous cystadenomas, 5 mucinous cystadenocarcinomas, 3 mucin-producing duct ectasias, and 2 papillary cystic epithelial neoplasms, were retrospectively reviewed. The examinations were obtained with 4 to 5 mm collimation with intravenous injection of 120-130 ml of contrast agent. RESULTS: Calcifications were found only in benign tumors (seven serous cyst-adenomas). Internal septations were found in benign and malignant tumors (seven serous cystadenomas, three benign mucinous cystadenomas, three mucinous cystadenocarcinomas). Solid excrescences within cystic cavities were found only in malignant tumors (two mucinous cystadenocarcinomas, two mucin-producing duct ectasias). Dynamic CT features allowed the distinguishing of serous cystadenomas from other cystic tumors and mucin-producing duct ectasias from other mucinous tumors. Dynamic CT features did not permit differentiation between benign mucinous cystadenomas, mucinous cystadenocarcinomas, and papillary cystic epithelial neoplasms. CONCLUSION: The review suggests that dynamic CT findings are useful to differentiate (a) serous cystadenomas and mucin-producing duct ectasias from other cystic tumors of the pancreas and (b) benign from malignant tumors. Such differentiation has impact on patient management.

Aged↗
PubMedDate not supplied

Contrast-enhanced fast MRI in differentiating brain toxoplasmosis and lymphoma in AIDS patients.

OBJECTIVE: Dynamic contrast-enhanced MRI was used to investigate space-occupying lesions of the brain in 22 AIDS patients without prior neurologic disease. Final diagnoses were toxoplasmosis in 13 patients (19 lesions), primary lymphoma in 7 patients (9 lesions), and both diseases in two (2 lesions, respectively). MATERIALS AND METHODS: Dynamic contrast-enhanced MRI was done by using a heavily T1-weighted GE sequence (TR/TE 100/5, 80 degrees flip angle) performed before and repeatedly for a period of 15 min after intravenous bolus injection of Gd-DOTA (0.1 mmol/kg). Signal enhancement of the lesions and normal brain was measured as the difference of signal intensity before and after intravenous administration of contrast medium. RESULTS: Lymphomas displayed significantly greater enhancement (mean 67%; SD 18%) than toxoplasmosis did (mean 34%; SD 16%; p < 0.001) on FLASH images. The enhancement ratios of the two lesions were significantly (p < 0.01) different between 30 and 600 s after injection. The difference between toxoplasmosis (mean 49%; SD 17%) and lymphoma (mean 69%; SD 26%) enhancement ratios on delayed SE images was less significant (p = 0.04). CONCLUSION: Preliminary evidence suggests that dynamic sequences increase the specificity of MR in distinguishing between toxoplasmosis and lymphoma, and this has important clinical implications.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Three-dimensional helical CT of intrahepatic venous structures: comparison of three rendering techniques.

OBJECTIVE: To define the advantages and disadvantages of various rendering techniques to obtain three-dimensional (3D) displays of intrahepatic venous structures with helical CT data. MATERIALS AND METHODS: After rapid preprocessing segmentation of the liver, helical CT data (8 mm slice thickness overlapped every 4 mm) from 10 patients were reconstructed using maximum intensity projection (MIP), volume rendering, and surface rendering algorithms. Three-dimensional imaging was evaluated blindly and independently by three observers for presence of artifacts and overall quality. RESULTS: Three-dimensional displays showed the hepatic veins and fifth order portal branches with the volume and MIP rendering techniques. Best overall quality in the 3D representation of the liver was achieved with the MIP technique (p < 0.05). Small details in venous anatomy and portal involvement by tumor were better imaged with the MIP technique. "Stair-step" artifacts markedly degraded the 3D displays obtained with the surface rendering technique, making it inappropriate for imaging the intrahepatic venous structures. CONCLUSION: Maximum intensity projection appears to be an adequate technique to perform 3D imaging of intrahepatic venous structures with helical CT data when 8 mm slice thicknesses overlapping every 4 mm are used. However, optimization of imaging protocols needs to be done and compared in a larger series.

Aged↗
PubMedDate not supplied

Focal nodular hyperplasia of the liver: assessment of hemodynamic and angioarchitectural patterns with gadolinium chelate-enhanced 3D spoiled gradient-recalled MRI and maximum intensity projection reformatted images.

PURPOSE: Our goal was to determine the relative merits of gadolinium chelate-enhanced 3D spoiled gradient-recalled (GRE) MRI versus maximum intensity projection (MIP) reformatted images in assessing the morphologic, hemodynamic, and angioarchitectural patterns of focal nodular hyperplasia (FNH) of the liver. METHOD: Ten consecutive patients with 10 FNHs had prospectively gadolinium chelate-enhanced 3D spoiled GRE MRI (TR/TE/FA = 10.1/1.9/30) of the liver at 1.5 T. Gadolinium chelate-enhanced 3D spoiled GRE source images and MIP reformatted images were separately analyzed with respect to morphologic and hemodynamic features and angioarchitectural patterns by two independent readers. RESULTS: Gadolinium chelate-enhanced 3D spoiled GRE source images and MIP reformatted images showed the most intense degrees of enhancement of FNH during the arterial phase of hepatic parenchymal enhancement in all cases. Gadolinium chelate-enhanced 3D spoiled GRE source images were superior to MIP reformatted images for the assessment of morphologic features of FNH (p < 0.02). MIP reformatted images were superior to the corresponding source images for showing the main branches of the hepatic artery, an arterial branch going to the FNH, and a small artery within the FNH radiating to peripheral areas (p < 0.05). There was excellent agreement between the two observers for analysis of the MIP reformatted images (p < 0.05). CONCLUSION: The combination of gadolinium chelate-enhanced 3D spoiled GRE source images and MIP reformatted images allows the analysis of morphologic, hemodynamic, and angioarchitectural patterns of FNH of the liver. Further study and comparison with currently applied strategies will determine the value of these two techniques for diagnosing FNH of the liver.

Adult↗
PubMedDate not supplied

CT of abdominal wall implantation metastases after abdominal percutaneous procedures.

PURPOSE: Our goal was to report the CT manifestations of abdominal wall implantation metastases occurring after abdominal percutaneous procedure. METHOD: CT scans and clinical data of six patients with abdominal wall implantation metastases at the puncture site following abdominal percutaneous procedure were reviewed. The abdominal percutaneous procedures included drainage of intraperitoneal abscess in patients with colon or gastric cancer (n = 2), transhepatic biliary drainage in a patient with hilar cholangiocarcinoma (n = 1), biopsy of intrahepatic hepatocellular carcinoma (n = 1), biopsy of a metastatic left adrenal gland (n = 1), and laparoscopic cholecystectomy in a patient with unsuspected gallbladder cancer (n = 1). RESULTS: CT enabled the diagnosis of abdominal wall implantation metastasis in all six patients and showed coexisting intraabdominal tumor sites in five patients. All abdominal wall implantation metastases were homogeneous before intravenous administration of iodinated contrast material and became moderately heterogeneous on contrast-enhanced CT scan with marked enhancement relative to adjacent tissues. CONCLUSION: Abdominal wall implantation metastases are moderately heterogeneous on contrast-enhanced CT scan with marked enhancement relative to adjacent tissues. In most cases of abdominal wall implantation metastasis following abdominal percutaneous procedure, CT shows additional intraabdominal tumor sites. This complication may occur following a variety of abdominal percutaneous procedures (either radiological or surgical).

Abdominal Muscles↗
PubMedDate not supplied

CT and MR imaging of benign hepatic and biliary tumors.

Benign hepatic and biliary tumors can present a difficult diagnostic challenge. Spiral computed tomography (CT) and magnetic resonance (MR) imaging are useful in the detection and characterization of these tumors. Imaging characteristics of lesions such as hepatic cyst, hemangioma, focal nodular hyperplasia (FNH), and hepatic adenoma are well known. Hepatic cysts demonstrate water attenuation at CT, are isointense relative to water at MR imaging, and do not enhance after intravenous administration of contrast material. Hemangiomas demonstrate characteristic nodular peripheral enhancement on early-phase images with subsequent fill-in centrally at both modalities. FNH classically demonstrates intense early enhancement with washout on delayed images. Although hepatic adenoma can also demonstrate intense early enhancement, it has a tendency to bleed and thus often appears more heterogeneous than FNH due to hemorrhage. Benign hepatic tumors that are less well described in the imaging literature include hepatic lipoma or angiomyolipoma, infantile hemangioendothelioma, and mesenchymal hamartoma. Hepatic lipoma has fat attenuation at CT, is isointense relative to fat at MR imaging, and does not enhance after intravenous administration of contrast material. Hepatic angiomyolipomas contain a variable amount of soft tissue in addition to fat and may therefore demonstrate enhancement at both modalities. The CT and MR imaging appearances of infantile hemangioma are similar to those of adult hemangioma. Infantile hemangioendothelioma occurs in infants under 6 months of age and is typically a larger lesion. Mesenchymal hamartoma also occurs in children, and its imaging appearance depends on the presence of stromal elements and the protein content of the cyst fluid. Familiarity with these imaging features can help distinguish particular disease entities.

Biliary Tract Neoplasms↗
PubMedDate not supplied

Ct evaluation of small bowel obstruction.

Although small bowel obstruction is a common occurrence, it is essential that this clinical condition be treated properly, that the site, level, and cause of obstruction be determined accurately, and that a tentative prognosis be formulated prior to surgery. The diagnosis of small bowel obstruction is based on a comprehensive approach that includes clinical background, patient history, and results of physical examination and laboratory tests. A variety of radiologic procedures are available to aid in the diagnosis of small bowel obstruction. Recent studies have demonstrated the superiority of CT in revealing the site, level, and cause of obstruction and in demonstrating threatening signs of bowel inviability. CT has proved useful in characterizing small bowel obstruction from extrinsic causes (adhesions, closed loop, strangulation, hernia, extrinsic masses), intrinsic causes (adenocarcinoma, Crohn disease, tuberculosis, radiation enteropathy, intramural hemorrhage, intussusception), intraluminal causes (eg, bezoars), or intestinal malrotation. Conventional radiography was the modality of choice for many years and should remain the initial imaging method in patients with suspected small bowel obstruction. However, the unique capabilities of CT in this setting make this modality an important additional diagnostic tool when specific disease management issues must be addressed.

Diagnosis, Differential↗