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Biomedical subjects

R Passariello

Publications and source records attributed to R Passariello.

At least 55 records · Page 3Linked to original sources
PubMed1999

MR cholangiopancreatography in malignant biliary obstruction.

Malignant lesions of the biliary tract are a frequent occurrence, typically presenting with clinical findings of obstructive jaundice. The authors discuss the role of MR cholangiopancreatography (MRCP) as a second level diagnostic technique, which can provide information regarding not only the location, but also the cause of the obstruction. This can be obtained if MRCP is considered as part of a complete study of the upper abdomen, with acquisition of T1- and T2-weighted images. The "all-in-one" approach may provide the identification, characterization, and staging of the lesion, giving the clinician all the information necessary for the planning of adequate treatment. Typical MR features of cholangiocarcinoma are provided, as well as conventional MR and MRCP findings in pancreatic carcinoma, periampullary carcinoma, and biliary obstruction secondary to hilar lymphadenopathy and metastatic lesions.

Bile Duct Neoplasms↗
PubMed1999

MR cholangiography of late biliary complications after liver transplantation.

OBJECTIVE: The aim of our study was to assess the role of MR cholangiography in the diagnosis of late biliary complications after liver transplantation. SUBJECTS AND METHODS: Twenty-three liver transplantation patients (18 men and five women; mean age, 46 years) underwent MR cholangiography using a nonbreath-hold, fat-suppressed three-dimensional turbo spin-echo sequence (TR/TE, 3000/700; echo train length, 128) optimized on a 0.5-T magnet. Inclusion criteria were liver function tests with abnormal results and hyperbilirubinemia with a clinical pattern not specific for biliary obstruction. All patients were referred by clinicians for contrast-enhanced cholangiography. Diagnostic confirmation was obtained with percutaneous transhepatic cholangiography (n = 4), endoscopic retrograde cholangiography (n = 8), T-tube cholangiography (n = 1), or clinical follow-up (n = 10). RESULTS: In 11 patients, no abnormalities of the biliary tract were revealed by MR cholangiography. In 11 patients, twelve strictures were diagnosed (nine anastomotic, two nonanastomotic-intrahepatic, and one nonanastomotic-extrahepatic, with association between anastomotic and nonanastomotic strictures in two cases). In one other patient, kinking of the common bile duct at the level of the anastomosis was observed. In all cases, MR cholangiography correctly showed the site of the stricture and the dilatation of bile ducts above, with excellent correlation with contrast-enhanced cholangiographic findings. Strictures were correctly graded in eight of 10 patients and were overestimated in two. Other findings included a 1-cm stone detected proximal to the obstructed common bile duct in one patient and multiple intrahepatic stones in another patient. CONCLUSION: MR cholangiography can show biliary obstruction and provide important information for planning therapeutic procedures.

Adult↗
PubMed1999

Localization of pancreatic insulinomas with MR imaging at 0.5 T.

OBJECTIVE: To determine the role of MR imaging in the localization of pancreatic insulinomas in patients with clinical and laboratory diagnosis of insulin-producing tumor. MATERIAL AND METHODS: Thirty-one patients presenting with signs and symptoms of pancreatic insulinomas were prospectively included in our study. Twenty-six patients underwent surgery, and pathologic specimens were examined: 5 patients, in whom the initial diagnosis of insulinoma was excluded, were also studied and then followed up. All patients were studied with a high gradient power 0.5 T magnet. Images were evaluated by 2 radiologists blinded to previous investigations, tests and results. RESULTS: MR imaging correctly localized 24 of the 26 insulinomas (2 were false-negative and 1 false-positive) and was correctly negative in the 5 control patients. The interobserver agreement had a kappa value of 0.89. CONCLUSION: MR imaging was accurate in localizing pancreatic insulinomas and as a consequence, patients in our institution are now submitted to surgery directly after the MR examination. Invasive methods are considered only in cases in which, despite clear biochemical results, MR imaging has not demonstrated a pancreatic focal lesion.

Adolescent↗
PubMed1999

MR pyelography and conventional MR imaging in urinary tract obstruction.

PURPOSE: To evaluate the possible role of MR imaging in the assessment of patients with urinary tract obstruction by combining conventional MR imaging and MR pyelography (MRP). MATERIAL AND METHODS: Forty-three patients with dilated upper urinary tract were studied with a high gradient strength 0.5 T magnet. Respiratory compensated T1-weighted, SE and T2-weighted TSE sequences were acquired in all patients. MRP images were obtained by using a respiratory compensated 3D T2-weighted TSE sequence. MRP images were reconstructed with a MIP algorithm. In all cases, urography and/or ascending pyelography were also performed. Images were independently evaluated by two radiologists. RESULTS: The dilated tract ureter and the level of the obstruction could be correctly demonstrated in all cases. The cause of the obstruction was correctly demonstrated by examiner 1 in 90% and by examiner 2 in 88%. The interobserver agreement was high with a kappa-value of 0.96. CONCLUSION: In cases of obstructive hydroureteronephrosis MR imaging, combining MRP and conventional sequences, can be proposed as an accurate technique in the assessment of level and cause of obstruction.

Aged↗
PubMed1999

[Magnetic resonance imaging and magnetic resonance cholangiopancreatography in evaluation of chronic pancreatitis. Part I: techniques and methods].

Until recently, MR examinations of the pancreas were limited by motion artifacts, vascular pulsatility and poor spatial resolution. Today, new techniques have been developed, which allow to overcome these problems and provide additional information such as selective images of biliary and pancreatic ducts and vascular structures. MR examinations of the pancreas need to include either breath-hold or nonbreath-hold morphological T1- and T2-weighted images; a contrast agent is required when the study is performed with fast imaging which allow the acquisition of dynamic images in arterial and portal venous phases. Recently, a new liver-specific contrast agent (Mn-DPDP) has been demonstrated to provide selective pancreatic enhancement. As a complement to baseline sequences, MR cholangiopancreatography images can be acquired, possibly integrated by functional examination after secretin administration. Finally, contrast-enhanced MR angiography opens new perspectives for vascular studies, particularly for the locoregional staging of pancreatic cancer.

Cholangiography↗
PubMed1998

Magnetic resonance imaging evaluation of myocardial perfusion.

Noninvasive qualitative/quantitative assessment of myocardial perfusion is considered to be fundamental in the management of known and suspected coronary artery disease patients, as shown by the widespread utilization of thallium-201- and technetium-99m-labeled agents in myocardial single-photon emission computed tomography (SPECT) scintigraphy for diagnostic as well as prognostic purposes. Recently, the availability of subsecond ultrafast magnetic resonance imaging (MRI) sequences (FLASH, TurboFLASH, EPI) has provided new avenues for assessing myocardial perfusion by MRI in conjunction with contrast-agent bolus administration (contrast-enhanced first-pass MRI). MRI contrast agents can be classified into relaxation agents (T1 "positive") and susceptibility agents (T2 star [T2*] "negative"). All the commercially available MRI contrast agents used in clinical practice are relaxation agents employing the T1 shortening effect of metal ions like gadolinium (paramagnetism), thus producing a tissue signal-intensity increase on T1-weighted images (positive enhancement). On the other hand, T2* agents induce mainly susceptibility effects, i.e., rapid dephasing of spins with resultant signal loss on T2*-sensitive sequences (negative enhancement). Unfortunately, both relaxation and susceptibility agents are, by definition, "extracellular" contrast media, as they rapidly diffuse into the interstitial space, thus hampering the simple application of indicator-dilution kinetics for myocardial perfusion assessment. Blood pool agents are therefore needed to obtain predictable relations between the concentration of contrast medium in the myocardium and the change in signal intensity. In addition, newer MRI techniques for tissue perfusion quantitation have been recently reported, based on blood-sensitive sequences, thus without intravenous contrast administration.

Contrast Media↗
PubMed1998

Pancreatic adenocarcinoma: combination of MR imaging, MR angiography and MR cholangiopancreatography for the diagnosis and assessment of resectability.

The purpose of this study was to determine the possibility of integrating MR cholangiopancreatography (MRCP) and MR angiography (MRA) to conventional MR images in the diagnosis and assessment of resectability of pancreatic adenocarcinoma. Twenty-three patients with pancreatic adenocarcinoma were prospectively examined with MR. Conventional MR images were acquired in all patients. Three-dimensional MRCP and MRA images were acquired in all patients with suspected biliary and vascular involvement. Acquisition time was less than 45 min in all cases. Images were independently evaluated by two radiologists, with final reading decided by consensus among readers. Diagnosis was confirmed with surgery in 16 patients and with percutaneous biopsy in 7. Concordance among readers was high with a kappa value of 0.83. Pancreatic adenocarcinoma was observed in all patients. Correct assessment of unresectability due to vascular involvement was found in 22 of 23 patients. Biliary obstruction was evident in 13 patients, involving the biliary and pancreatic ducts in 9 and the biliary ducts only in 4. Technical advances permit extensive use of MRI in the evaluation of abdominal pathologies. The combination of MR imaging, MRCP, and MRA can provide sufficient information for the diagnosis and assessment of resectability of pancreatic adenocarcinoma, which otherwise would require three different exams.

Adenocarcinoma↗
PubMed1998

MR cholangiography: techniques and clinical applications.

Magnetic resonance cholangiography (MRCP) is a new non-invasive imaging technique for the evaluation of bilio-pancreatic disorders. Different sequences, using both breathhold and non-breathhold techniques, have been employed in order to obtain MRCP images. The authors discuss the technical aspects, particularly focusing their attention on a non-breathhold, three-dimensional, fat-suppressed turbo-spin-echo sequence, optimized on a 0.5-T magnet with 15 mT/m gradients. Clinical applications of MRCP are evaluated, presenting data from both the literature and personal experience. The main indication for MRCP study is represented by the evaluation of common bile duct obstruction, with the aim of assessing the presence of the obstruction (accuracy 85-100 %) and, subsequently, its level (accuracy 91-100 %) and its cause. The utility of associating conventional MR images to MRCP in malignant strictures in order to characterize and stage the malignant lesions is also discussed. Finally, data are presented regarding the indications and utility of MR pancreatography in the evaluation of patients with chronic pancreatitis.

Biliary Tract↗
PubMed1998

Hepatocellular carcinoma treatment with percutaneous ethanol injection: evaluation with contrast-enhanced color Doppler US.

PURPOSE: To investigate the ability of contrast agent-enhanced color Doppler ultrasonography (US) in evaluating the response of hepatocellular carcinoma (HCC) to percutaneous ethanol injection (PEI). MATERIALS AND METHODS: Forty-two patients (36 men, six women; age range, 51-79 years) with 54 1.3-7.0-cm-diameter (mean +/- SD, 2.8 cm +/- 1.1) HCC lesions were examined with contrast-enhanced color Doppler US before and after PEI. Spiral computed tomography (CT) and percutaneous biopsy also were performed to establish the outcome of therapy. RESULTS: Before PEI, intratumoral color signals were demonstrated at contrast-enhanced color Doppler US in 47 (87%) lesions (in 40 patients). After PEI, blood flow signals were no longer detected in all 34 of the lesions that were found to be necrotic at spiral CT and biopsy. In 12 (92%) of 13 lesions containing residual viable tumor, intratumoral color signals corresponding to the enhancing areas at spiral CT were still identified at contrast-enhanced color Doppler US. These 12 lesions were retreated with PEI by targeting the areas of residual tumor with contrast-enhanced color Doppler US guidance. Complete necrosis was seen after the second PEI cycle in nine of 12 lesions. CONCLUSION: Contrast-enhanced color Doppler US shows promise in assessing the therapeutic effect of PEI on HCC and in guiding additional treatment in cases of incomplete response.

Aged↗
PubMed1998

[New prospects in the assessment of the knee extensor complex with dynamic magnetic resonance].

INTRODUCTION: Altered patellofemoral biomechanics may result in pain, instability and early involutive processes. Magnetic Resonance Imaging (MRI), with its panoramic capabilities, has proved to be an effective technique in the study of knee extensor complex changes. The diagnostic advantages of dynamic studies of patellofemoral kinetics are reported in the recent scientific literature. We investigated the diagnostic potentials of passive studies of the knee extensor complex with sagittal and axial cine MRI. Then, we developed and optimized an innovative study method overcoming the limitations of the other dynamic techniques for the correct assessment of patellofemoral biomechanics. MATERIAL AND METHODS: We studied the knee with a .2 T permanent magnet dedicated to the limbs and acquired the images in different positions of flexion-extension with T1-weighted SE and T2-weighted GE sequences. We examined 21 healthy volunteers and 37 of 38 patients with anterior knee joint pain of suspected patellofemoral origin. All the images needed for dynamic studies were acquired in about 20 minutes. For the scan planes not to be affected by patellar motion in the different degrees of knee extension, it is necessary to acquire single axial images to be edited in cine motion afterwards. Each acquisition is aligned along sagittal reference planes depiciting always the same patellar aspect. RESULTS: Significant correlations were found between clinical and cine MR findings in 25 patients. In particular we depicted some extensor complex impingement conditions missed at conventional MRI, which clarified the role played by patellar dysplastic changes in cartilage microtraumas. Our technique was accurate, quite easy to perform and repeatable. We performed cost-effective dynamic studies which were useful in the evaluation of patients with anterior knee pain in whom conventional MRI had failed to provide enough information. CONCLUSIONS: Our technique differs from other passive or active dynamic studies reported on in the literature because the patellar volume does not change during acquisitions. This permits to decrease morphological changes and to simplify, on cine MR reconstructions, the specific analysis of patellofemoral dynamics during flexion-extension. Fewer morphological changes also mean a more accurate analysis showing the role of patellar dysplasia in cartilage microtraumas. Our dynamic MR protocol is accurate, easy to perform and to repeat; it allows dynamic studies in the patients with poor static MR findings.

Humans↗
PubMed1998

[Virtual endoscopy with a volumetric reconstruction technic: the technical aspects].

OBJECTIVE: We analyze the peculiar technical features of virtual endoscopy obtained with volume rendering. MATERIAL AND METHODS: Our preliminary experience is based on virtual endoscopy images from volumetric data acquired with spiral CT (Siemens, Somatom Plus 4) using acquisition protocols standardized for different anatomic areas. Images are reformatted at the CT console, to obtain 1 mm thick contiguous slices, and transferred in DICOM format to an O2 workstation (Silicon Graphics, Mountain View CA, USA) with processor speed of 180 Mhz, 256 Mbyte RAM memory and 4.1 Gbyte hard disk. The software is Vitrea 1.0 (Vital Images, Fairfield, Iowa), running on a Unix platform. Image output is obtained through the Ethernet network to a Macintosh computer and a thermic printer (Kodak 8600 XLS). RESULTS: Diagnostic quality images were obtained in all the cases. Fly-through in the airways allowed correct evaluation of the main bronchi and of the origin of segmentary bronchi. In the vascular district, both carotid strictures and abdominal aortic aneurysms were depicted, with the same accuracy as with conventional reconstruction techniques. In the colon studies, polypoid lesions were correctly depicted in all the cases, with good correlation with endoscopic and double-contrast barium enema findings. In a case of lipoma of the ascending colon, virtual endoscopy allowed to study the colon both cranially and caudally to the lesion. The simultaneous evaluation of axial CT images permitted to characterize the lesion correctly on the basis of its density values. DISCUSSION: The peculiar feature of volume rendering is the use of the whole information inside the imaging volume to reconstruct three-dimensional images; no threshold values are used and no data are lost as opposite to conventional image reconstruction techniques. The different anatomic structures are visualized modifying the reciprocal opacities, showing the structures of no interest as translucent. The modulation of different opacities is obtained modifying the shape of the opacity curve, either using pre-set curves or in a completely independent way. Other technical features of volume rendering are the perspective evaluation of the objects, color and lighting. In conclusion, volume rendering is a promising technique to elaborate three-dimensional images, offering very realistic endoscopic views. At present, the main limitation is represented by the need of powerful and high-cost workstations.

Aged↗