Biomedical subjects

R C Semelka

Publications and source records attributed to R C Semelka.

At least 19 recordsLinked to original sources

PubMed2003

Early-enhancing non-neoplastic lesions on gadolinium-enhanced MRI of the liver.

AIM: To assess the frequency, cause, and significance of early-enhancing, non-neoplastic (EN) lesions on gadolinium-enhanced magnetic resonance imaging (MRI) of the liver performed for the detection of malignant hepatic tumours. MATERIALS AND METHODS: From September 1997 to September 2000, we reviewed the images of 125 patients, suspected of having hepatic tumours, in whom (1) gadolinium-enhanced triphasic dynamic gradient-recalled-echo (GRE) imaging in addition to unenhanced T1- and T2-weighted MRI was performed, (2) conventional angiography and combination computed tomography (CT) hepatic arteriography and CT during arterial portography were performed within 2 weeks of the MRI, and (3) definitive surgery within 2 weeks of the MRI or follow-up study by means of intravenously contrast-enhanced CT or MRI in 10 months or more was performed. Angiographic studies were correlated to determine the underlying causes of the EN lesions. RESULTS: We found 78 EN lesions in 36 patients (29%), ranging in size from 4 and 50 mm (mean, 12.2 mm). From the MR reports, our radiologists had prospectively diagnosed EN lesions as probable malignant tumours in eight (10%), possible malignant tumours in 36 (46%), and probable non-neoplastic lesion in 34 (44%). EN lesions were found in 27 of 81 (33%) cirrhotic patients and in nine of 44 (20%) non-cirrhotic patients. Fifty-one EN lesions (65%) were located along the liver edge. The shape was circular in 42 (54%), oval in 14 (18%), irregular in 12 (15%), wedge-shaped in seven (9%), and fan-shaped in three (4%). Twenty EN lesions (26%) appeared slightly hyperintense on T2-weighted images. The causes were non-neoplastic arterio-portal shunting in 48 (62%), cystic venous drainage in four (5%), rib compression in four (5%), aberrant right gastric venous drainage in two (3%), and unknown in 20 (26%). CONCLUSION: Over half the number of EN lesions were caused by non-neoplastic arterio-portal shunting, occasionally showing slight hyperintensity on T2-weighted images. On MR images the non-neoplastic nature of the EN lesion was often ascertained. Radiologists should not overcall EN lesions as malignant as the patients involved would be inappropriately considered inoperable. In problematic cases, further investigation with angiographic CT or follow-up imaging studies should be performed.

Aged↗

PubMed2001

Adrenal adenomas: characteristic postgadolinium capillary blush on dynamic MR imaging.

We sought to evaluate dynamic post-gadolinium contrast enhanced magnetic resonance (MR) imaging characteristics of adrenal adenomas with comparison to those of malignant adrenal tumors. MR images, including in- and out-of-phase spoiled gradient echo (SGE) and dynamic gadolinium enhancement, of 35 adrenal adenomas in 34 patients, and 12 malignant adrenal tumors in 12 patients, were reviewed retrospectively. MR images were assessed for the presence of a capillary blush on immediate postgadolinium SGE images, and for rapid washout of contrast on 45-second postgadolinium SGE images. Thirty-five adrenal adenomas (mean size, 3.1 cm) and 12 malignant adrenal tumors (mean size, 7.4 cm) were assessed. Of 35 adrenal adenomas, 25 (71%) showed a homogeneous capillary blush on immediate postgadolinium images. Thirty-three (94%) adrenal adenomas demonstrated rapid washout on 45-second postgadolinium images (P < 0.001). Of 35 adrenal adenomas, 30 (86%) showed diminished signal intensity (SI) on out-of-phase images. Of 12 malignant adrenal tumors, none showed a homogeneous capillary blush on immediate postgadolinium images. Six (50%) malignant tumors showed negligible enhancement, four (33%) showed irregular patchy enhancement, and two (17%) showed peripheral enhancement (P < 0.001). On 45-second postgadolinium images, 11 (92%) of 12 malignant adrenal tumors showed irregular enhancement. In the majority of adrenal adenomas, an initial homogeneous capillary blush and rapid washout are demonstrated on gadolinium-enhanced dynamic MR imaging. Our preliminary results suggest that this may provide useful complementary information to the appearance of adrenal masses on in- and out-of-phase images.

Adenoma↗

PubMed2001

Chronic hepatitis: correlation of early patchy and late linear enhancement patterns on gadolinium-enhanced MR images with histopathology initial experience.

The purposes of our study were to describe the early and late enhancement patterns of the liver on gadolinium-enhanced dynamic magnetic resonance (MR) images in patients with chronic hepatitis and to correlate these findings with histopathology. Patients were entered into the study based on the presence of chronic hepatitis, imaging evaluation with MR imaging (MRI), including early and late postgadolinium images, and histopathologic correlation. Early and late dynamic postgadolinium MR images of 29 consecutive patients with a pathologically proven diagnosis of chronic hepatitis were retrospectively evaluated for the presence of three types of enhancement, i.e., homogeneous, linear, and patchy. Correlation was made between the enhancement patterns on MR images and blinded retrospective interpretation of the histopathologic specimens, which were obtained within 3 months of the MR examination. Of the 29 patients, 16 (55.2%) patients showed patchy enhancement on the early gadolinium-enhanced MR images. In 11 (68.8%) of these 16 patients, histopathology demonstrated numerous macrophages, variable hepatocyte necrosis, and increased steatosis. The remaining 13 (44.8%) patients showed homogeneous enhancement on the early gadolinium-enhanced MR images. In 11 (84.6%) of these 13 patients, histopathology demonstrated few or no macrophages, little or no hepatocellular necrosis, and little or no steatosis. The correlation between patchy enhancement and acute liver inflammation was significant (P = 0.005). On the late gadolinium-enhanced MR images, 20 (69.0%) of 29 patients showed prominent linear enhancement. In 19 (95.0%) of these 20 patients, histopathology revealed hepatic fibrosis. We concluded that in patients with chronic hepatitis, the presence of early patchy enhancement indicates either concurrent or recent hepatocellular damage, whereas the presence of late linear enhancement indicates the presence of fibrosis, with a high degree of correlation with histopathologic findings.

Adolescent↗

PubMed2001

Focal liver lesions: comparison of dual-phase CT and multisequence multiplanar MR imaging including dynamic gadolinium enhancement.

The purpose of this study was to compare dual-phase spiral computed tomography (CT) and magnetic resonance imaging (MRI) using dynamic gadolinium enhancement for liver lesion detection and characterization. Twenty-two consecutive patients underwent dual-phase spiral CT and MRI for the evaluation of focal liver disease within a 1-month period. Spiral CT and MR images were interpreted prospectively, in a blinded fashion by separate, individual, experienced investigators, to determine lesion detection and characterization. Liver lesions were confirmed by surgery and pathology in 6 patients, and by clinical and imaging follow-up in the other 16 patients. Pathological correlation of a primary extrahepatic malignancy was available in 5 of the 16 patients who had metastatic liver disease. Spiral CT and MRI detected 53 and 63 lesions, and characterized 39 and 62 true positive lesions, respectively. A kappa statistic test was applied to assess agreement between MR and CT results. MR versus CT for lesion detection resulted in a kappa statistic of 0.54 (95% confidence interval), indicating moderate agreement, and 0.32 (95% confidence interval) for lesion characterization, indicating only slight agreement. More lesions were detected on MR images than CT images in 6 (27%) patients, with lesions detected only on MR images in 4 (18%) patients. More lesions were characterized on MR images in 9 (41%) patients. In 9 patients with a discrepancy between MR and CT findings, the MR images added information considered significant to patient management in all 9 cases. MRI was moderately superior to dual-phase spiral CT for lesion detection, and was markedly superior for lesion characterization, with these differences having clinical significance.

Adult↗

PubMed2001

MRI of carcinoid tumors: spectrum of appearances in the gastrointestinal tract and liver.

The purpose of this study was to evaluate the spectrum of appearances of gastrointestinal carcinoid tumors at magnetic resonance imaging (MRI) and to elucidate patterns of appearances of carcinoid liver metastases on precontrast and postgadolinium images. The MR examinations of 29 patients (11 men, 18 women; age range, 33-87 years) with histologically confirmed gastrointestinal carcinoid tumors, representing our complete 9.5 years of experience with this entity, were retrospectively reviewed. Twelve patients had MR examinations prior to resection or biopsy of the primary tumor (preoperative group); 17 patients were imaged postsurgically (postoperative group). All MR studies were performed at 1.5 T and comprised T1-weighted spoiled gradient echo (SGE), T2-weighted fat-suppressed turbo spin echo, HASTE, and serial postgadolinium T1-weighted SGE sequences without and with fat suppression. Morphology, signal intensity, and contrast enhancement of primary tumors and of metastases to the mesentery, peritoneum, and liver were evaluated. Primary tumors were visualized in 8 of 12 patients and best demonstrated on postgadolinium T1-weighted fat-suppressed images. The appearance of primary tumors was a nodular mass originating from the bowel wall (4 of 12 patients) or regional uniform bowel wall thickening (4 of 12 patients) with moderate intense enhancement on postgadolinium images. In 4 of 12 patients the primary tumor was prospectively not seen. Mesenteric metastases, seen in eight patients, presented as nodular masses and were associated with mesenteric stranding in seven patients. A total of 156 liver metastases were evaluated in 16 patients. On precontrast T1- and T2-weighted images, 117 metastases (75%) were hypointense and hyperintense, respectively. A total of 146 metastases (94%) were hypervascular, showing moderate intense enhancement during the hepatic arterial phase, and 9 metastases (6%) were hypovascular. Twenty-three metastases (15%) were visible only on immediate postgadolinium images. MRI is able to demonstrate findings in carcinoid tumors, including the primary tumor, mesenteric metastases, and liver metastases. Liver metastases are commonly hypervascular and may be demonstrable only on immediate postgadolinium images.

Adult↗

PubMed2001

Radiologic diagnosis and staging of pancreatic ductal adenocarcinoma.

This article presents imaging modalities in the diagnosis and staging of pancreatic ductal adenocarcinoma. Magnetic resonance imaging (MRI) and endoscopic ultrasonography (EUS) have the highest accuracy in detection of pancreatic cancer. MRI and EUS have similar accuracy in determining the local extent of pancreatic cancer. Angiography, computed tomography (CT) angiography and EUS are similarly accurate in evaluating peripancreatic vascular involvement. MRI is the superior method for detecting liver metastases and peritoneal implants of pancreatic ductal adenocarcinoma. Endoscopic retrograde cholangiopancreatography (ERCP) and magnetic resonance cholangiopancreatography (MRCP) are used to assess the biliary tract of patients with pancreatic cancer. Positron emission tomography (PET) is useful in distinguishing pancreatic cancer from focal pancreatic inflammation.

Adenocarcinoma↗

PubMed2001

Radiologic features of cystic, endocrine and other pancreatic neoplasms.

This article presents imaging features of cystic, endocrine and other pancreatic neoplasms. Microcystic adenoma which is composed of small cysts (<2 cm), its macrocystic subgroup contains solitary cyst. Multiple cysts larger than 2 cm are associated with mucinous cystic neoplasm. Swiss cheese appearence with central calcification is characteristic for microcystic adenomas. Septal and mural enhancement as well as larger size (>2 cm) are accounted for mucinous cystic neoplasms, its variant along pancreatic duct is ductectatic mucinous cystic neolasm. Endocrine tumors of pancreas are hypervascular and can be depicted on early dynamic enhanced crosssectional imaging modalities or on angiography when they are <1 cm. Pancreatic metastases and lymphomas are rare neoplasms which should also be included in differential diagnosis for pancreatic masses.

Cystadenocarcinoma↗

PubMed2001

Exophytic benign tumors of the liver: appearance on MRI.

The purpose of our study was to determine the MR imaging appearance of exophytic benign liver tumors on precontrast and postgadolinium images. We reviewed our 9.5 year experience with MRI of the liver with dynamic gadolinium enhanced imaging to identify four patients with five histologically proven exophytic benign liver tumors. The histological diagnoses were cavernous hemangioma (2), focal nodular hyperplasia (FNH) (1), and hepatocellular adenoma (HCA) (2 exophytic adenomas in a patient with adenomatosis of the liver). All MRI studies were performed at 1.5 T and included: in-phase and out-of-phase T1-weighted spoiled gradient echo (SGE), T2-weighted fat-suppressed echo train spin echo, single shot T2-weighted sequences, and serial postgadolinium T1-weighted SGE sequences without and with fat-suppression. Prospective interpretations were reviewed and retrospective consensus readings of all MR images were performed assessing location, size, origin, morphology, visibility of the connection to the liver, signal characteristics on precontrast T1-weighted and T2-weighted images, and enhancement patterns on serial postgadolinium images. Three of the five tumors were pedunculated and connected to the liver by a thin stalk, which was prospectively identified in one patient. On precontrast and serial postgadolinium images, all exophytic tumors showed signal characteristics comparable to imaging features of standard intraparenchymal benign liver tumors. Our findings illustrate that the characteristic T1, T2, and postgadolinium imaging findings of these tumors permit correct identification of their liver origin despite their exophytic location, even if their connection with liver is not visualized.

Adenoma, Liver Cell↗

PubMed2001

MR imaging findings of infectious cholangitis.

The purpose of this study was to evaluate the appearance of infectious cholangitis on MRI. The MR images of 13 patients (9 women, 4 men; age range, 14-79 years) with clinically confirmed infectious cholangitis, who represent our complete 9.5 year experience with this entity, were retrospectively evaluated. All MR studies were performed at 1.5 T and included: in-phase and out-of-phase T(1)-weighted spoiled gradient echo (SGE), T(2)-weighted fat-suppressed echo train spin echo, single shot T(2)-weighted sequences, and serial postgadolinium T(1)-weighted SGE sequences without and with fat-suppression. The biliary ductal system was evaluated regarding presence of dilatation, stenosis, wall irregularities, wall thickening, and gadolinium enhancement of duct walls. The liver parenchyma was evaluated regarding focal signal abnormalities on precontrast and serial postgadolinium images. Biliary ductal dilatation was observed in 100% of patients. Mild to moderate thickening of bile duct walls combined with increased enhancement on postgadolinium images was observed in 92% of patients. The liver parenchyma showed periportal or wedge-shaped areas of hyperintense signal on T(2)-weighted images in 69% of patients. On T(1)-weighted images, 54% of patients showed areas of hypointense signal and 15% of patients showed wedge-shaped hyperintense areas. Areas with increased enhancement on immediate postgadolinium SGE were observed in 58% of patients, and in 42% of patients increased enhancement persisted on 2 min postgadolinium fat-suppressed images. Distinctive MRI findings on pre- and postgadolinium images are appreciated for infectious cholangitis.

Bacterial Infections↗

PubMed2001

Acute renal failure: common occurrence of preservation of corticomedullary differentiation on MR images.

The purpose of this study was to evaluate the relationship between renal corticomedullary differentiation (CMD) on MR imaging and serum creatinine (sCr) level in patients with acute renal failure (ARF). Twenty-one patients with ARF were retrospectively investigated. In all 21 patients, sCr levels were obtained on the same date as the MR study, and within 8 days before and after the MR study. CMD was assessed on non-contrast T(1)-weighted images and immediate post-gadolinium spoiled gradient echo (Gd-SGE) images. Presence of CMD was graded into 3 groups as 'preserved', 'intermediate', or 'loss'. On non-contrast T(1)-weighted images, 12/21 (57%) showed loss of CMD and 9/21 (43%) showed preserved CMD. On immediate Gd-SGE images, 5/21 (24%) showed loss of CMD, 12/21 (57%) preserved CMD, and 4/21 (19%) intermediate CMD. The sCr levels of 9 patients with preserved CMD on non-contrast T(1)-weighted images ranged from 1.4 to 10.5 mg/dl (mean 4.6 mg/dl), while those of 12 patients with loss of CMD ranged from 1.6 to 7.6 mg/dl (mean 4.8 mg/dl), which was not statistically significant (p > 0.2). Renal CMD can remain preserved on non-contrast T(1)-weighted or immediate Gd-SGE images in patients with acute presentation of ARF, independent of sCr level.

Acute Kidney Injury↗

PubMed2001

MRI evaluation of the liver.

Following the introduction of rapid, high-quality scan techniques and the development of new, tissue-specific contrast agents, the applications of magnetic resonance imaging (MRI) for liver imaging continue to grow. MRI using a T1-weighted sequence, T2-weighted sequence, and serial gadolinium-enhanced gradient echo sequences is very effective at both detecting and characterizing various hepatic lesions. The use of a growing number of contrast agents has the potential to increase the sensitivity and specificity of liver MRI in numerous pathological conditions by improving morphological and functional information. This article examines the current status of liver MRI, highlighting technical and methodological approaches, contrast agents, and main clinical applications. MRI appears to be an ideal diagnostic tool for the detection and characterization of liver disease.

Contrast Media↗

PubMed2001

Contrast agents for MR imaging of the liver.

A variety of different categories of contrast agents, and within each category a number of individual agents, are currently available for clinical use in magnetic resonance (MR) imaging of the liver. In this review, the use of nonspecific extracellular gadolinium chelates, reticuloendothelial system-specific iron oxide particulate agents, hepatocyte-selective agents, and combined perfusion and hepatocyte-selective agents are described. Most clinical experience is with nonspecific extracellular gadolinium chelates. The relatively low cost, safety, good patient tolerance, and ability to help detect and characterize a wide range of liver diseases have rendered gadolinium chelates as commonly used agents. Reticuloendothelial system-specific agents improve lesion detection by decreasing the signal intensity of background liver on T2-weighted MR images, which increases the conspicuity of focal hepatic lesions with negligible reticuloendothelial cells (eg, metastases). Hepatocyte-selective agents increase the signal intensity of background liver on T1-weighted images, which increases the conspicuity of focal lesions that do not contain hepatocytes (eg, metastases). The clinical application of the different categories of contrast agents, techniques for their administration, sequences to be used, and appearances of common entities on contrast agent-enhanced studies are described.

Contrast Media↗

PubMed2001

New contrast agents for imaging the liver.

The contrast agents suited for hepatic imaging can be divided into nonspecific, extracellular space- (ECS) directed, reticuloendothelial system- (RES) selective, and hepatocyte-selective compounds. There is a wide variation in regard to biodistribution, pharmacokinetics, contrast behavior, and tissue specificity. The ECS contrast agents provide information on vascularization and perfusion similar to that of X-ray contrast agents. The RES- and hepatocyte-specific contrast agents offer more "functional" information that may enhance tissue characterization; however, the biology of the different hepatocellular and nonhepatocellular tumors is limiting the diagnostic efficacy of the tissue-specific compounds in many respects.

Animals↗

PubMed2001

Imaging of benign and malignant focal liver lesions.

Over the past 15 years, MR imaging of the abdomen and pelvis has progressed significantly. Although initially found to be useful as an adjunct to CT imaging for selective applications, MR imaging now is establishing a role as a primary diagnostic technique. Increasing evidence shows that MR imaging has advantages over CT regarding diagnostic sensitivity and specificity for many abnormalities of solid organs, bile and pancreatic ducts, bowel, peritoneum, and retroperitoneum. This article discusses and contrasts current MR and CT techniques for imaging the liver and discusses the relative ability to identify and diagnose focal liver disease.

Contrast Media↗

PubMed2000

Budd-Chiari syndrome: spectrum of appearances of acute, subacute, and chronic disease with magnetic resonance imaging.

The purpose of this study was to describe our collective experience in the magnetic resonance (MR) investigation of patients with proven acute, subacute, and chronic Budd-Chiari syndrome and to demonstrate the spectrum of appearances on T1- and T2-weighted as well as dynamic post-gadolinium spoiled gradient-echo imaging. All patients with proven Budd-Chiari syndrome who underwent MR examinations between June, 1992 and October, 1998 were included in the study. Fourteen patients were included in the study: four with acute, three with subacute, three with chronic, and four with acute superimposed on either subacute (two) or chronic (two) Budd-Chiari syndrome. MR imaging features were retrospectively evaluated to determine: a) liver morphology, b) pattern of signal intensity (SI) on T1-weighted images, c) pattern of SI on T2 weighted images, d) dynamic enhancement characteristics, e) presence or absence of visible venous thrombosis, and f) presence or absence of venous macroscopic collaterals. The MR findings were correlated with surgical, histopathological, and laboratory data to determine imaging characteristics related to the chronicity of the disease process. Hepatic venous thrombosis or absence of hepatic venous flow was demonstrated in all patients in the study. In the four patients with acute Budd-Chiari syndrome, the liver periphery was moderately low signal on T1 and moderately high signal on T2-weighted images relative to the central liver; both early and late gadolinium-enhanced images revealed diminished peripheral enhancement. In the three patients with subacute Budd-Chiari syndrome, the liver periphery was moderately low signal on T1, and moderately high signal on T2-weighted images, while early and late gadolinium-enhanced images revealed heterogenously increased enhancement within the liver periphery. In the three patients with chronic Budd-Chiari syndrome, the SI differences between peripheral and central liver were minimal on T1- and T2-weighted images, and enhancement differences were also minimal. Extensive bridging intrahepatic and capsular venous collaterals were visualized in chronic cases. In the four patients with acute Budd-Chiari syndrome superimposed on more chronic disease, a combination of gadolinium enhancement patterns was observed on MR images. Enhancement patterns between central and peripheral liver were different for acute, subacute, and chronic Budd-Chiari syndromes, suggesting differentiation between these phases of the disease process. Application of this pattern approach permitted recognition of acute changes superimposed on more chronic disease.

Acute Disease↗

PubMed2000

Polyposis syndromes of the gastrointestinal tract: MR findings.

We describe the magnetic resonance (MR) findings in patients with gastrointestinal polyposis syndromes using breath-hold T1-weighted sequences, both standard and with fat suppression, prior to and following gadolinium administration, and breathing-independent single-shot half-Fourier RARE T2-weighted sequences. Six patients with gastrointestinal polyposis syndromes underwent MR examination to investigate for the presence of metastatic disease. The appearances of the gastrointestinal polyps on noncontrast T1-weighted spoiled gradient-echo (SGE), T2-weighted (half-Fourier RARE) images, and early and late gadolinium-enhanced SGE images were determined. Other gastrointestinal findings and extragastrointestinal disease were also evaluated. Patients with the following gastrointestinal polyposis syndromes were included: familial polyposis (n = 3), Peutz-Jeghers syndrome (n = 1), Gardner's syndrome (n = 1), and neurofibromatosis (n = 1). Polypoid lesions in all patients exhibited signal intensity comparable to bowel on noncontrast images and enhanced similar to bowel on early and late gadolinium-enhanced images. Polyps larger than 2 cm, observed in one patient with familial polyposis and the patient with Gardner's disease, showed mild heterogeneity on late gadolinium-enhanced fat-suppressed images. Multiple colonic polyps ranging from 5 mm to 3 cm in diameter were observed in patients with familial adenomatous polyposis. A solitary 1.5 cm polyp associated with entero-enteric intussusception was observed in the patient with Peutz-Jeghers syndrome. Gastric polyps ranging from 5 mm to 6 cm were observed in the stomach of the patient with Gardner's syndrome. Duodenal and jejunal neurofibromas ranging from 1 to 2 cm in diameter were present in the patient with neurofibromatosis. Extra gastrointestinal findings included an adrenal adenoma (1 patient), a pheochromocytoma (1 patient), and liver metastases (2 patients). Gastrointestinal polyps in patients with polyposis syndromes may be visualized on MR images employing breath-hold T1-weighted and breathing-independent snapshot T2-weighted techniques. Appreciation of polyp enhancement on post-gadolinium images is an important finding, which should help distinguish polyps from bowel contents.

Adenomatous Polyposis Coli↗

PubMed2000

Neuroendocrine tumors of the pancreas: spectrum of appearances on MRI.

We reviewed our 8.5 year experience with magnetic resonance imaging (MRI) in the demonstration of neuroendocrine tumors of the pancreas using precontrast fat-suppressed T1-weighted, fat-suppressed T2-weighted, and serial post-gadolinium T1-weighted images, to describe the spectrum of appearances of these tumors. All MR examinations of patients with histologically proven neuroendocrine tumors were retrospectively reviewed. Histological type, tumor location, tumor diameter, signal intensity on precontrast images, enhancement patterns, and presence and appearance of metastases were determined. Twenty-two patients had histologically proved neuroendocrine tumors detected by MRI over the 8.5 year period. Histological types were gastrinoma (n = 8), insulinoma (n = 3), glucagonoma (n = 2), somatostatinoma (n = 1), VIPoma (n = 1), ACTHoma (n = 1), carcinoid (n = 1), and five untyped tumors. Primary tumors ranged in diameter from 1 to 6.2 cm. There was one histopathology-proven false-positive neuroendocrine tumor. The positive predictive value for MRI in the detection of these tumors was 96%. The most common appearance on precontrast images was low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, which was observed in tumors in 18 of 22 patients. Moderate or intense early enhancement of all or portions of the primary tumors was observed in tumors in 19 of 22 patients either as uniform homogeneous, ring, or diffuse heterogeneous enhancement. Enhancement was minimal on these images in the other three patients. Gastrinomas enhanced in a ring pattern in 7 of 8 patients whereas the majority (9 of 11 patients) of noninsulinoma-nongastrinoma and untyped tumors enhanced in a diffuse heterogeneous fashion. Liver metastases were present in 13/22 patients including 3/8 with gastrinoma and 9/11 with noninsulinoma-nongastrinoma tumors. Most neuroendocrine tumors of the pancreas are low signal intensity on fat-suppressed T1-weighted images and moderately high in signal intensity on fat-suppressed T2-weighted images, although variations do exist. Tumors most often enhance in an early moderately intense fashion. Gastrinomas are often different in appearance than other neuroendocrine tumors in that they usually enhance in a ring fashion whereas nongastrinoma-noninsulinoma tumors usually enhance in a heterogeneous fashion.

Adult↗

PubMed2000

Breath-hold 3D gradient-echo MR imaging of the lung parenchyma: evaluation of reproducibility of image quality in normals and preliminary observations in patients with disease.

This study evaluates the reproducibility and image quality of a three-dimensional (3D) gradient-echo sequence for imaging the lung parenchyma, with and without gadolinium administration, using a 2D spoiled gradient-echo sequence for comparison. Twenty patients without lung disease (normals) and five patients with lung disease (lung disease) underwent paired 2D and 3D gradient-echo sequences, without contrast (24 patients) and with contrast (18 patients). Images were retrospectively reviewed independently in a blinded fashion by two investigators. Artifacts and demonstration of central lung, peripheral lung, heart, pulmonary arteries, and esophagus were evaluated. Image quality of the central lung was rated as fair or good in 5 and 4 (reader one and two) patients with non-contrast 2D gradient-echo, 24 and 25 patients with non-contrast 3D gradient-echo, 3 and 1 patient(s) with contrast-enhanced 2D gradient-echo, and 19 and 19 patients with contrast-enhanced 3D gradient-echo imaging. Differences in image quality between 2D and 3D sequences were significant (P < 0.001). Heart-related phase artifacts were negligible in 2 and 0 patients with non-contrast 2D gradient-echo, 23 and 25 patients with non-contrast 3D gradient-echo, 0 and 0 patients with contrast-enhanced 2D gradient-echo, and 17 and 19 patients with contrast-enhanced 3D gradient-echo imaging. Differences in heart-related phase artifact in the central lung between 2D and 3D sequences were significant (P = 0.001). Infiltrates, lung cancer, and pulmonary metastasis were better shown on the gadolinium-enhanced 3D gradient-echo sequences than on the other sequences. Breath-hold 3D gradient-echo imaging results in good image quality and negligible image artifacts and is superior to 2D spoiled gradient-echo imaging. Preliminary results in patients with disease appear promising.

Artifacts↗