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Biomedical subjects

R L Baron

Publications and source records attributed to R L Baron.

At least 73 records · Page 4Linked to original sources
PubMed1993

Confluent hepatic fibrosis in advanced cirrhosis: appearance at CT.

To determine the computed tomographic (CT) characteristics of confluent fibrosis complicating liver cirrhosis, CT scans of 420 cirrhotic patients without hepatic malignancy who underwent hepatic transplantation were correlated with freshly resected whole liver specimens. In 59 patients, CT demonstrated 70 focal abnormalities corresponding to confluent fibrosis. The lesions were characterized by shape and location: 49 wedge-shaped lesions radiated from the porta hepatis, eight peripheral bandlike lesions were remote from the porta hepatis, and 13 lesions were seen as total lobar or segmental fibrosis. Associated volume loss was seen in 62 of the 70 lesions as retraction of the overlying hepatic capsule or total shrinkage of the segmental or lobar involvement. At plain CT, all 70 lesions were areas of lower attenuation than adjacent liver. At contrast material-enhanced CT, 51 of 64 lesions were iso-attenuating or minimally hypo-attenuating. The authors conclude that confluent fibrosis has a characteristic appearance at CT. Recognition of its characteristics may help radiologists differentiate confluent fibrosis from hepatic neoplasms in cirrhotic patients.

Adolescent↗
PubMed1993

Hepatic CT enhancement: a method to demonstrate reproducibility.

Optimal techniques for intravenous administration of contrast material in computed tomographic (CT) examination of the liver remain controversial mainly because of inaccurate methods of data evaluation. This study tested the reproducibility of hepatic contrast material enhancement within the same patient and the accuracy of two methods of data analysis. Fourteen patients received identical CT examinations. Attenuation of liver and vessels was measured before and after administration of contrast material, and enhancement was calculated for each image. Data were analyzed by averaging enhancement values obtained over 5- and 10-second intervals and by using a new computer program that creates an enhancement-time curve and measures area under the curve (AUC) for any specific time interval. Data were compared between patients' first and second examinations. Mean liver enhancement was nearly identical at all time intervals with the AUC technique. Analysis of interpatient data showed marked variability of all parameters at all measured time intervals, suggesting that results from comparative studies within the same patient may be more accurate than those for studies of two different treatment groups. The AUC technique is preferable to other methods of data analysis for contrast enhancement evaluation.

Adult↗
PubMed1993

Confluent hepatic fibrosis in advanced cirrhosis: evaluation with MR imaging.

PURPOSE: To assess the usefulness of magnetic resonance (MR) imaging in diagnosis of confluent fibrosis in patients with advanced cirrhosis. MATERIALS AND METHODS: Findings on pretransplantation MR images were compared with findings on pretransplantation computed tomographic (CT) scans and posttransplantation gross appearance and histologic findings in 11 patients with confluent fibrosis. In all patients, MR imaging was performed before and after administration of gadopentetate dimeglumine. RESULTS: Nine lesions appeared wedge shaped and involved the medial segment of the left lobe, anterior segment of the right lobe, or both; two lesions consisted entirely of lobar or segmental fibrosis. Associated volume loss in the affected regions was seen in 10 lesions. All 11 lesions were hypoattenuating on non-contrast material-enhanced CT scans. CONCLUSION: Findings on MR images corresponded well to CT findings and gross appearance. MR imaging provided useful morphologic information about confluent fibrosis, but the MR signal characteristics are not unique and do not enable differentiation from hepatic neoplasms.

Contrast Media↗
PubMed1992

Hepatocellular carcinoma: reduced frequency of typical findings with dynamic contrast-enhanced CT in a non-Asian population.

Four computed tomographic (CT) findings have been described as typical or diagnostic of hepatocellular carcinoma: Primary morphologic findings include tumor encapsulation and fatty metamorphosis and secondary findings include venous invasion and arterioportal shunting. However, virtually all of the articles reporting these findings with significant frequency have been from Japan and thus represent an almost purely Asian population. The authors analyzed a series of 93 patients with hepatocellular carcinoma, only eight of whom were Asian. With the exception of venous invasion (48%), the analysis showed that while the four CT features may be typical of hepatocellular carcinoma, three features occurred with low frequency in a non-Asian population: tumor encapsulation, 12%; fatty metamorphosis, 0%; and arterioportal shunting, 4%. In addition, a review of the literature showed that all of the findings have occurred in other hepatic neoplasms, including benign and metastatic tumors.

Carcinoma, Hepatocellular↗
PubMed1992

Patterns of intrahepatic bile duct dilatation at CT: correlation with obstructive disease processes.

The authors performed a blinded, retrospective analysis of 100 computed tomographic (CT) scans of patients with proved extrahepatic bile duct obstruction, including primary sclerosing cholangitis (PSC), to determine whether certain patterns of intrahepatic bile duct dilatation are suggestive of specific disease processes. Among 30 patients with benign obstructive disease, CT showed pruning of the intrahepatic ducts in four patients (13%), beading in four (13%), and skip dilatations in one (3%). Among 54 patients with malignant obstructive disease, CT illustrated pruning in eight (15%) patients, beading in 11 (20%), and skip dilatations in two (4%). Among 16 patients with PSC, CT demonstrated pruning in four (25%), beading in two (13%), and skip dilatations in five (31%). The majority of patients with malignant or benign obstructive disease or PSC had intrahepatic duct dilatation in both lobes of the liver. It extended into the periphery in 46 of 54 patients (85%) with malignant obstructive disease, in 20 of 30 (67%) with benign obstructive disease, and in 10 of 16 (63%) with PSC. The CT finding of skip dilatations is strongly suggestive of PSC. The CT findings of pruning and beading are nonspecific and may be observed at CT in patients with bile duct obstruction due to a wide variety of causes. The distribution and extent of intrahepatic duct dilatation at CT do not differ among biliary disease processes.

Bile Duct Neoplasms↗
PubMed1992

Posttransplant lymphoproliferative disorder: intrathoracic manifestations.

Posttransplant lymphoproliferative disorder (PTLD) is a serious complication of organ transplantation and immunosuppression. Early diagnosis and treatment greatly affect prognosis. Chest radiographs (n = 13), chest computed tomographic (CT) scans (n = 2), or both (n = 20) from 35 patients with intrathoracic PTLD were retrospectively studied to define the intrathoracic manifestations of this disorder. Intrathoracic abnormalities consisted of pulmonary nodules (16 patients), patchy air-space consolidation (three patients), mediastinal and hilar adenopathy (17 patients), thymic enlargement (two patients), pericardial thickening and/or effusions (two patients), and pleural effusions (four patients). Multiple, well-circumscribed pulmonary nodules with or without mediastinal adenopathy are highly suggestive of PTLD. However, pathologic examination is usually necessary for a definitive diagnosis.

Adolescent↗
PubMed1992

Hepatic parenchymal perfusion defects detected with CTAP: imaging-pathologic correlation.

To determine whether characteristics of focal hepatic parenchymal perfusion defects detected with computed tomographic arterial portography (CTAP) correlate with underlying pathologic processes, 245 perfusion defects detected with CTAP in 60 patients who subsequently underwent definitive hepatic surgery were characterized by shape, location within the liver, and relative attenuation value and were prospectively correlated with sectioned pathologic specimens. Of 177 round perfusion defects, 102 (58%) were malignant and 75 (42%) were benign. Only one (2%) of 53 peripheral wedge-shaped defects was malignant. All 15 peripheral flat defects were benign. Defects in characteristic locations anterior to the porta hepatis (n = 15) and adjacent to the intersegmental fissure (n = 7) were uniformly benign. While 83 (56%) of 147 soft-tissue attenuation defects were malignant, only four (6%) of 68 intermediate-attenuation defects were malignant. Although these characteristics of parenchymal perfusion defects aid in differentiation of benign from malignant processes, all other types of perfusion defects are nonspecific and may require biopsy.

Adenoma, Bile Duct↗
PubMed1992

Epithelioid hemangioendothelioma of the liver: imaging findings with pathologic correlation.

Hepatic epithelioid hemangioendothelioma is a rare malignant neoplasm that has nonspecific clinical signs and symptoms and can be difficult to diagnose on the basis of biopsy results. Radiologists may suggest the diagnosis of this slowly progressive neoplasm by recognizing its characteristic radiologic features. We correlated images from CT (13), sonography (nine), and MR (six) with pathologic findings in resected whole livers (eight) and biopsy specimens (five) from 13 patients 25-58 years old. Gross pathologic examination showed a repetitive pattern of multiple solid tumor nodules, in a predominantly peripheral distribution, with coalescence as individual nodules exceeded 4 cm. Tumor nodules had a hyperemic rim. Lesions adjacent to the capsule often produced capsular retraction. These findings correlated well with imaging findings. On CT, the lesions were of low attenuation, peripherally based, and with capsular retraction or flattening in nine (69%) of 13 patients. Unenhanced CT scans showed superior conspicuity over contrast-enhanced CT scans (9/13, 69%) and showed the extent of lesions more accurately in all cases (13/13, 100%). In nine patients, lesions had a peripheral enhancement pattern of alternating attenuation values correlating with the hyperemic rim at pathologic evaluation. On sonograms, the tumors were solid and predominantly hypoechoic. On MR, tumor signal was low on T1-weighted and high on T2-weighted images, with a low-signal halo present around many of the lesions. CT, sonographic, or MR findings of coalescent peripheral hepatic masses with capsular retraction are highly suggestive of hepatic epithelioid hemangioendothelioma.

Adult↗
PubMed1992

Detection of malignant tumors in end-stage cirrhotic livers: efficacy of sonography as a screening technique.

OBJECTIVE: Patients with hepatic cirrhosis are at an increased risk of developing primary malignant tumors of the liver. If these tumors are discovered early, current therapies may be curative. We conducted a prospective study to assess the accuracy of sonographic screening for the detection of malignant tumors in cirrhotic livers as determined by correlation with resected whole livers. SUBJECTS AND METHODS: A total of 200 prospectively interpreted preoperative sonograms from 200 patients with cirrhosis who underwent hepatic transplantation were correlated with specimens of freshly resected whole livers. The results were analyzed to determine the sensitivity and specificity of sonography in identifying patients with malignant tumors and detecting individual tumors in each patient. RESULTS: Pathologic examination showed 80 malignant lesions in 34 patients (28 with hepatocellular carcinoma, three with cholangiocarcinoma, two with metastases, and one with non-Hodgkin's lymphoma) and three hemangiomas in two patients. Sonography correctly showed malignant tumors in 17 of the 34 patients, for a sensitivity of 50%. Sonograms were false-positive for malignant tumors in three patients, two of whom had a total of three hemangiomas. Sonography correctly showed 36 of the 80 malignant lesions, for a lesion sensitivity of 45% and specificity of 98%. Of the 44 missed lesions, 24 were 1 cm or less, 12 were between 1 and 3 cm, and eight were more than 3 cm in diameter. CONCLUSION: Our results show that sonography is highly insensitive in the detection of malignant lesions in end-stage cirrhotic livers and thus is not a reliable screening technique. However, because of sonography's very high specificity, any sonographically identified lesion in a cirrhotic liver should be considered malignant until proved otherwise.

Carcinoma, Hepatocellular↗
PubMed1991

Hyperintense cirrhotic nodules on MRI.

Descriptions of regenerating nodules of cirrhosis indicate that they are often isointense to liver parenchyma on magnetic resonance imaging (MRI). Regenerating nodules of cirrhosis can occasionally appear hypointense on all MRI sequences due to iron deposition within the nodules. We reviewed 21 cases of pathologically proven mixed or macronodular cirrhosis using MRI. In five patients, nodules appeared as hyperintense to liver parenchyma on short TR/TE images and were isointense on long TR/TE or GRASS images. In another five cases, nodules appeared hypointense on either long TR/TE or GRASS images, and corresponding hypointense nodules were observed on short TR/TE images in one of these patients. Our findings suggest that regenerating nodules of cirrhosis may have a more variable appearance on short TR/TE images.

Carcinoma, Hepatocellular↗
PubMed1991

A phantom for facilitating in vitro computed tomographic studies of gallstones.

A phantom was designed and constructed for in vitro studies of gallstones using a computed tomographic (CT) scanner. A primary objective of the design was to permit studies of multiple gallstones in a single CT slice. This was accomplished by incorporating in the phantom removable compartments that contain vertically oriented, cone-shaped voids for holding the gallstones and surrounding fluid medium. A slice through the center of the phantom passes through the apex of each cone-shaped holder, and hence through the center of each gallstone. The main body of the phantom is made of water-mimicking plastic, and each compartment can accommodate gallstones ranging up to 3 cm in diameter. Initial experience with the phantom has shown it to be a successful design.

Cholelithiasis↗
PubMed1991

Gallstone susceptibility to in vitro fragmentation by a 480-nm pulsed dye laser. Correlation with computed tomography characteristics.

The object of this investigation was to determine gallstone susceptibility to laser lithotripsy and to discover whether this susceptibility is related to the computed tomography (CT) appearance of gallstones. Gallstones collected from surgery were scanned by CT and classified as homogeneously dense (greater than 90 Hounsfield units [HU]), homogeneously faint (30-60 HU), or rimmed. Sixty stones were subjected to laser energy at 20, 40, 60, 80, or 100 mJ. Fracture and fragmentation (all particles less than 2 mm) were assessed in relation to the energy level setting and number of laser pulses delivered. The authors found that a 480-nm, flashlamp-pumped pulsed dye laser can fragment completely all the types of human gallstones that were tested, although there is significant variability in gallstone susceptibility to laser lithotripsy. This susceptibility varies with CT appearance: dense stones require fewer pulses and lower energies for fracture and fragmentation, compared to faint or rimmed stones. The authors anticipate that CT characterization of gallstones may be a clinically useful screening tool before laser lithotripsy.

Cholelithiasis↗
PubMed1991

Improved fat suppression in STIR MR imaging: selecting inversion time through spectral display.

By observing the fat-signal peak on the spectral display of a magnetic resonance (MR) imager while varying inversion time (TI), the authors determined the TI that produced the lowest fat peak for the best suppression of fat signal in subsequent short-TI inversion-recovery (STIR) MR imaging. In 25 volunteers who underwent imaging at multiple TIs, the TI that produced the lowest measured fat signal intensity was the same as that selected by means of TI tuning in 60% of cases and was within 5 msec in the remaining 40%.

Adipose Tissue↗
PubMed1991

Comparison of STIR and spin-echo MR imaging at 1.5 T in 45 suspected extremity tumors: lesion conspicuity and extent.

Short inversion time inversion recovery (STIR) imaging and a double-echo spin-echo (SE) sequence at 1.5 T in 45 sequential patients with suspected extremity tumors were compared to assess the number of lesions detected, subjective conspicuity of lesions, approximate volume of abnormality detected in each lesion, and identification of peritumoral brightening in tissues adjacent to each lesion. STIR sequences enabled detection of all 45 lesions; 44 were detected with the SE sequence. Tumor appeared most conspicuous on STIR images in 35 patients (78%) and was most conspicuous on SE images in 10 patients (22%). Peritumoral brightening, which indicated either peritumoral edema or microscopic tumor infiltration, was detected in 20 patients but was detected only with STIR sequences in nine patients. It is concluded that, although STIR and SE sequences are comparable for lesion detection in the extremities, most lesions appear more conspicuous with STIR. STIR may enable detection of a greater volume of abnormality than SE sequences and may therefore have important implications for local staging and surgical and radiation therapy planning.

Adolescent↗
PubMed1991

Root of the superior mesenteric artery in pancreatitis and pancreatic carcinoma: evaluation with CT.

To determine if changes involving the root of the superior mesenteric artery are specific for neoplasm, the authors retrospectively reviewed 173 computed tomographic (CT) examinations of patients with proved pancreatitis (103 examinations) and pancreatic ductal adenocarcinoma (70 examinations). Streaky infiltration of the fat surrounding the root was seen in 27 of 56 examinations of acute pancreatitis, in four of 24 examinations of chronic pancreatitis, in 12 of 23 examinations of pancreatitis complicated by abscess, and in 25 of 70 examinations of pancreatic carcinoma. Periarterial lymph nodes were visible in 14 with acute pancreatitis, in three with chronic pancreatitis, in six with pancreatic abscess, and in 11 with pancreatic carcinoma. A focal mass extended to within 1 cm of the root in 10 with acute pancreatitis, in two with chronic pancreatitis, in four with pancreatic abscess, and in 24 with pancreatic carcinoma; the mass obliterated the periarterial fat in seven with acute pancreatitis, in one with pancreatic abscess, and in 18 with pancreatic carcinoma. Circumferential encasement occurred in one with chronic pancreatitis, in four with pancreatic abscess, in 14 with pancreatic carcinoma, and in none with acute pancreatitis; nearly all cases of encasement revealed loss of periarterial fat. Thus, these indicators are not specific for neoplasm.

Abscess↗