Biomedical subjects

Katsuyoshi Ito

Publications and source records attributed to Katsuyoshi Ito.

17 recordsLinked to original sources

PubMed2007

Small hepatic lesions found on single-phase helical CT in patients with malignancy: diagnostic capability of breath-hold, multisection fluid-attenuated inversion-recovery (FLAIR) MR imaging using a half-fourier acquisition single-shot turbo spin-echo (HASTE) sequence.

PURPOSE: To evaluate the diagnostic capability of breath-hold, multisection fluid-attenuated inversion-recovery (FLAIR) imaging using a half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence in combination with T2-weighted fast spin-echo (FSE) magnetic resonance (MR) sequences for small hepatic lesions found on CT in patients with malignancy. MATERIALS AND METHODS: This study included 48 patients with extrahepatic malignancy who underwent both CT and MR examinations. There were a total of 112 small hepatic lesions (73 cysts and 39 liver metastases, <2 cm in diameter) that showed low attenuation on enhanced CT. Three radiologists independently reviewed the CT and MR (FLAIR-HASTE and T2-weighted FSE) images and assigned a confidence level to their evaluation (cyst or metastasis) on a five-point scale. RESULTS: All three reviewers were significantly better able (P < 0.05) to differentiate small hepatic cyst from liver metastasis with combined FLAIR-HASTE and T2-weighted FSE images (Az values = 0.997-0.999) than with CT (0.917-0.932). The mean values of sensitivity, specificity, and accuracy were significantly higher (P < 0.001) for T2-weighted FSE with FLAIR-HASTE (96.6%, 96.8%, and 96.7%, respectively) than for CT (76.9%, 61.6%, and 67.3%, respectively). A confident diagnosis was rendered in 12 of 112 lesions (10.7%) on the basis of CT, and this rate increased to 83 of 112 (74.1%) on the basis of T2-weighted FSE and FLAIR-HASTE imaging. CONCLUSION: FLAIR-HASTE is considered to be an effective sequence for differentiating hepatic cysts from liver metastases without the use of a contrast agent. With FLAIR-HASTE one can confidently diagnose small hepatic lesions found on CT in patients with a malignancy.

Adolescent↗

PubMed2006

Hepatocellular carcinoma: conventional MRI findings including gadolinium-enhanced dynamic imaging.

A great variety of MR pulse sequences for hepatocellular carcinomas (HCCs) are now available. In this article, we reviewed the current MR imaging techniques that are routinely used for hepatic imaging, and described the optimization of these sequences as well as the utility and characteristics of each sequence for the accurate diagnosis of HCCs. Then, we reviewed various MR imaging findings of advanced and early HCCs with emphasis on signal intensity and hemodynamic patterns. Finally, we described the value of multi-arterial-phase contrast-enhanced dynamic MR imaging of the whole liver with excellent temporal resolution for evaluating transitional hemodynamics of hepatic lesions during the six arterial phases.

Carcinoma, Hepatocellular↗

PubMed2006

Percutaneous radiologic gastrostomy using push-type gastrostomy tubes with CT and fluoroscopic guidance.

OBJECTIVE: The purpose of this study was to evaluate the safety and feasibility of percutaneous radiologic gastrostomy with endoscopic push-type gastrostomy tubes using CT and fluoroscopic guidance. CONCLUSION: Percutaneous radiologic gastrostomy using CT and fluoroscopic guidance with push-type tubes is a safe and effective means of gastric feeding that has few complications and offers an alternative to introducer-placed gastrostomy tubes.

Aged↗

PubMed2005

Differentiation between hepatic cyst and hemangioma: additive value of breath-hold, multisection fluid-attenuated inversion-recovery magnetic resonance imaging using half-Fourier acquisition single-shot turbo-spin-echo sequence.

PURPOSE: To evaluate the additive value of breath-hold, multisection fluid-attenuated inversion-recovery (FLAIR) magnetic resonance imaging (MRI) using half-Fourier acquisition single-shot turbo-spin-echo (HASTE) sequence as supplements to moderately and heavily T2-weighted fast-spin-echo (FSE) sequences in differentiating hepatic cyst from hemangioma. MATERIALS AND METHODS: A total of 183 lesions (127 hepatic cysts, 56 hepatic hemangiomas) in 117 patients were evaluated in this study. Three radiologists independently reviewed FLAIR MR images using a HASTE sequence and T2-weighted FSE MR images. Each radiologist used a five-point scale to rate his confidence in determination of hepatic cyst and hemangioma. RESULTS: All three reviewers were significantly better able to differentiate hepatic cyst from hepatic hemangioma with the combination of FLAIR imaging using HASTE and moderately and heavily T2-weighted FSE images (area under the receiver operating characteristic (ROC) curve, 0.99 for each reader) than with moderately and heavily T2-weighted FSE images alone (0.82-0.93; P < 0.05). FLAIR-HASTE imaging in addition to T2-weighted FSE sequences improved the diagnostic performance, including the sensitivity, specificity, accuracy, and confident diagnosis in the differentiation between hepatic hemangiomas and cysts. CONCLUSION: FLAIR-HASTE imaging is useful for distinguishing hepatic hemangioma from hepatic cyst without the use of contrast-enhanced MR images.

Adult↗

PubMed2005

Pre- and postprandial alterations of portal venous flow: evaluation with single breath-hold three-dimensional half-Fourier fast spin-echo MR imaging and a selective inversion recovery tagging pulse.

PURPOSE: To evaluate the influence of food intake on portal flow using unenhanced magnetic resonance imaging (MRI). MATERIALS AND METHODS: The study population included 29 healthy subjects. A selective inversion recovery tagging pulse was used on the superior mesenteric vein (SMV) and splenic vein (SpV) to study the correlation of tagged blood in the portal vein (PV). MRI was performed before and 60-90 min after a meal. RESULTS: The flow signal from the SMV increased in 97% of the subjects after the meal. Before the meal the portal flow was dominated by flow from the SpV in 59% of the subjects, while it was dominated by flow from the SMV in 76% of the subjects after the meal. The most common distribution pattern of the flow signal from the SpV before the meal was in the central part of the main PV (55%), while it was in the left side (45%) after the meal. The most common distribution pattern of the flow signal from the SMV was in the bilateral sides of the main PV both before and after the meal (62%). CONCLUSION: This technique shows potential for evaluating pre- and postprandial alterations of flow from the SpV and SMV in the PV under physiological conditions.

Adult↗

PubMed2005

Does T2-weighted MR imaging improve preoperative detection of malignant hepatic tumors? Observer performance study in 49 surgically proven cases.

The purpose of our study was to determine whether or not the addition of T2-weighted fast spin-echo (SE) imaging to gadolinium-enhanced spoiled gradient-recalled-echo (GRE) imaging improves the observer performance in the preoperative detection of malignant hepatic tumors. Gadolinium-enhanced GRE and fat-suppressed T2-weighted fast SE images obtained in 49 patients with 82 surgically confirmed malignant hepatic tumors (40 hepatocellular carcinomas and 42 metastases) were retrospectively reviewed by three independent off-site observers. In the random review of images, gadolinium-enhanced GRE images were reviewed first; thereafter, T2-weighted fast SE images were added for combined review. Observer performance was evaluated with the McNemar's test and receiver operating characteristic curve analysis. For gadolinium-enhanced GRE images alone vs. combined images, sensitivities for detection were 78% vs. 79% for hepatocellular carcinomas (P>.05), 67% vs. 71% for metastases (P<.05) and 72% vs. 75% for tumors overall (P<.05), respectively. The Az values were 0.892 vs. 0.889 in hepatocellular carcinomas (P>.05), 0.797 vs. 0.828 in metastases (P<.05) and 0.839 vs. 0.846 in tumors overall (P>.05), respectively. Our results showed that the addition of T2-weighted fast SE imaging to gadolinium-enhanced GRE imaging improved the observer performance in the detection of metastases.

Adult↗

PubMed2004

Imaging diagnosis of cirrhosis and chronic hepatitis.

Cirrhosis is an end stage of chronic diffuse liver disease, characterized by irreversible hepatic fibrosis. Cirrhosis slowly progresses from chronic hepatitis to early cirrhosis and finally to advanced cirrhosis with the increasing risk of complications, and causes regional morphologic changes of the liver during the course of the disease, according to disease severity. MR imaging is better able to provide comprehensive information about cirrhosis or chronic hepatitis and their complications than any other imaging modality currently available. In this article, we reviewed the spectrum of imaging findings of cirrhosis and chronic hepatitis, including regional changes of hepatic morphology, several signs of early and advanced cirrhosis, nodular liver surface, hepatic iron deposition, regenerative nodules, and varices and portosystemic collaterals.

Hepatitis B, Chronic↗

PubMed2004

Hepatic enhancement in multiphasic contrast-enhanced MDCT: comparison of high- and low-iodine-concentration contrast medium in same patients with chronic liver disease.

OBJECTIVE: The aim of this study was to evaluate the degree of hepatic enhancement and image quality in patients with cirrhosis or chronic hepatitis who underwent multiphasic contrast-enhanced dynamic imaging on MDCT at least twice using standard (300 mg I/mL) and higher (370 mg I/mL) iodine concentrations in contrast medium during follow-up periods. MATERIALS AND METHODS: This study included 20 patients with chronic liver diseases who underwent at least two multiphasic contrast-enhanced dynamic MDCT examinations using 100 mL of standard (300 mg I/mL = group A) and higher (370 mg I/mL = group B) iodine concentrations in contrast medium. After we obtained unenhanced CT scans, we performed multiphasic scanning at 30 sec (arterial phase), 60 sec (portal phase), and 180 sec (late phase) after the start of contrast medium injection. The CT values of hepatic parenchyma, abdominal aorta, and portal vein were measured. The mean enhancement value was defined as the difference in CT values between unenhanced and contrast-enhanced images. Visual image quality was also assessed on the basis of the degree of hepatic and vascular enhancement, rated on a 4-point scale. RESULTS: The mean hepatic parenchyma enhancement values in group B was significantly greater (p < 0.001) than those in group A during the portal phase (43.8 +/- 8.2 H vs 36.2 +/- 7.3 H) and the late phase (33.7 +/- 7.0 H vs 27.3 +/- 3.9 H), but the difference on the arterial phase images between the two groups (9.4 +/- 3.2 H vs 8.3 +/- 2.5 H) was not significant. The mean aorta-to-liver contrast during the arterial phase in group B was significantly higher (p < 0.001) than that in group A (236 +/- 40 H vs 193 +/- 32 H). For qualitative analysis, the mean visual scores for hepatic parenchyma and vasculature enhancement in group B were significantly higher than those in group A in arterial phase (p < 0.018), portal phase (p < 0.0001), and late phase (p < 0.0001). CONCLUSION: In the same patients with chronic liver diseases, a higher iodine concentration (370 mg I/mL) in the contrast medium improves contrast enhancement of liver parenchyma in the portal phase and late phase images, improves overall image quality, and helps improve diagnostic accuracy for liver diseases on multiphasic contrast-enhanced dynamic MDCT.

Aorta, Abdominal↗

PubMed2004

Multiarterial phase dynamic MRI of small early enhancing hepatic lesions in cirrhosis or chronic hepatitis: differentiating between hypervascular hepatocellular carcinomas and pseudolesions.

OBJECTIVE: The purpose of this study was to assess the value of multiarterial phase contrast-enhanced dynamic MRI of the whole liver obtained during a single breath-hold for small early enhancing hepatic lesions in patients with cirrhosis or chronic hepatitis, emphasizing the distinction between hypervascular hepatocellular carcinomas and pseudolesions. MATERIALS AND METHODS: The study population included 40 patients with cirrhosis or chronic hepatitis who had small early enhancing hepatic lesions (a total of 70 lesions: 40 hepatocellular carcinomas, 30 pseudolesions). All patients underwent multiarterial phase contrast-enhanced dynamic MRI (six phases) of the whole liver during a single breath-hold. RESULTS: Twenty-one (53%) of 40 hypervascular hepatocellular carcinomas showed rapid central washout after early enhancement of the lesion as well as peritumoral coronal enhancement, but these findings were not observed in any hypervascular pseudolesions (p < 0.001). In 19 hepatocellular carcinomas without rapid central washout, early enhancement of the lesion appeared at the second, third, or fourth phase (mean, 2.5 phases). In eight of these 19 hepatocellular carcinomas, lesion enhancement disappeared by the sixth phase. Conversely, in 30 hypervascular pseudolesions, early enhancement of the lesion appeared at the second, third, fourth, or fifth phase (mean, 3.0 phases). In 28 of these 30 pseudolesions, lesion enhancement continued until the sixth phase. CONCLUSION: Rapid central washout after the early enhancement of the lesion and coronal enhancement surrounding the lesion are highly specific and diagnostic findings of small hypervascular hepatocellular carcinomas if present at multiarterial phase contrast-enhanced dynamic MRI. Hypervascular pseudolesions tend to show prolonged enhancement during the arterial phase compared with hypervascular hepatocellular carcinomas.

Aged↗

PubMed2003

Right posterior hepatic notch sign: a simple diagnostic MR finding of cirrhosis.

PURPOSE: To determine the frequency of occurrence of the right posterior hepatic notch sign at MR imaging in patients with cirrhosis, and to assess its diagnostic capability of this sign as a simple diagnostic MR finding of cirrhosis. MATERIALS AND METHODS: This study population included 330 patients with pathologically proved cirrhosis (N = 202) or without clinical evidence of chronic liver diseases (N = 128, control group). MR images were qualitatively evaluated for the presence of the right posterior hepatic notch sign. This sign was considered present if there was a sharp notch in the right posterior surface of the liver. The presence of the expanded gallbladder fossa sign was also evaluated during the same reading session. RESULTS: The right posterior hepatic notch sign was observed in 145 of the 202 patients in the cirrhosis group, while this sign was seen in only two of the 128 patients in the control group (P < 0.0001). The sensitivity, specificity, and accuracy of this sign for the MR diagnosis of cirrhosis were 72%, 98%, and 82%, respectively. When the presence of either the expanded gallbladder fossa sign or the right posterior hepatic notch sign was considered for the MR diagnosis of cirrhosis, the sensitivity and accuracy increased to 86% and 89%, respectively. CONCLUSION: The right posterior hepatic notch sign can be used as a simple and highly specific sign of cirrhosis, if present. The diagnostic performance can be improved when the presence of either the expanded gallbladder fossa sign or the right posterior hepatic notch sign was considered.

Case-Control Studies↗

PubMed2003

Cirrhosis or chronic hepatitis: evaluation of small (<or=2-cm) early-enhancing hepatic lesions with serial contrast-enhanced dynamic MR imaging.

PURPOSE: To evaluate the frequency and clinical importance of small (<or=2 cm) early-enhancing hepatic lesions in cirrhotic liver disease with serial multiphasic contrast material-enhanced dynamic magnetic resonance (MR) imaging. MATERIALS AND METHODS: The study population included 208 patients with cirrhosis (n = 162) or chronic hepatitis (n = 46) who underwent dynamic contrast-enhanced MR imaging at least twice during the clinical course, with at least a 12-month interval between the initial and latest MR examinations. Initial images were evaluated for the presence and shape of small (<or=2 cm) early-enhancing hepatic lesions at arterial-phase contrast-enhanced MR imaging. If a small early- enhancing lesion was seen on the initial image, the latest follow-up image was reviewed to assess the serial changes in the features of a specific lesion. RESULTS: One hundred fifty-eight small early-enhancing lesions were detected in 75 (36%) of the 208 patients on the initial MR images. Of those 158 lesions, 104 were round or oval, 30 wedge-shaped, 18 geographic (irregularly shaped), and six triangular. Among the 104 round or oval lesions, 54 (52%) disappeared or decreased in size on the latest MR images and were considered definite pseudolesions. Twenty-nine (28%) of the 104 round or oval lesions were classified as hepatocellular carcinoma (HCC) on the basis of their interval growth or pathologic confirmation. The remaining 21 (20%) lesions were stable in size and appearance and considered probable pseudolesions. For the other three shapes, 73% of wedge-shaped, 78% of geographic, and 67% of triangular lesions disappeared or decreased in size. CONCLUSION: Small early-enhancing hepatic lesions in patients with cirrhosis usually showed no interval growth or disappeared during serial contrast-enhanced dynamic MR imaging. Even though these lesions are round or oval, they may more frequently be pseudolesions than HCCs.

Adult↗

PubMed2002

Cirrhosis: MR imaging features.

The intent of this article is to provide a comprehensive review of MR imaging findings of cirrhosis and discusses clinical implications. Areas of focus include: (1) Morphologic changes of the liver in advanced cirrhosis and in early cirrhosis, (2) the frequency and imaging spectrum of intra- and extrahepatic changes in cirrhosis such as regenerative nodules, nodular liver surface, hepatic iron deposition, fibrosis, dilation of right inferior phrenic artery, gastrointestinal wall thickening, and portal hypertension, (3) serial MR findings of clinically progressive cirrhosis, (4) newly described MR sign of cirrhosis (an expanded gallbladder fossa sign), and (5) complications after liver transplantation. Understanding these MR features related to cirrhosis is helpful in clinical MR practice.

Humans↗

PubMed2002

Cirrhosis: modified caudate-right lobe ratio.

PURPOSE: To determine whether a modified caudate-right lobe ratio (C/RL) with use of the right portal vein to set the lateral boundary (C/RL-r) is more accurate for diagnosing cirrhosis and evaluating its clinical severity than is the previously described C/RL with use of the main portal vein to set the lateral boundary (C/RL-m). MATERIALS AND METHODS: Two hundred thirty-six patients (121 with pathologically proved cirrhosis and 115 without history of chronic hepatic diseases) underwent magnetic resonance (MR) imaging. Two independent observers measured C/RL-r and compared it with C/RL-m. Results were compared by using receiver operating characteristic (ROC) curves and accuracy measures at various thresholds. RESULTS: The area below the ROC curve was greater for C/RL-r (0.797) than for C/RL-m (0.731; P =.040). By using a C/RL-r greater than 0.90, the sensitivity, specificity, and accuracy for the MR imaging diagnosis of cirrhosis were 71.7%, 77.4%, and 74.2%, respectively. The highest accuracy of the C/RL-m was 65.7%, when the C/RL-m was greater than 0.55. Interobserver agreement was statistically confirmed for both measurements by using kappa analysis. Significant differences were found among the three Child-Pugh classes by using C/RL-r (P =.0105) but not by using C/RL-m. CONCLUSION: C/RL-r is more accurate for diagnosing cirrhosis and evaluating its clinical severity than is C/RL-m.

Adult↗

PubMed2002

Intraportal venous flow distribution: evaluation with single breath-hold ECG-triggered three-dimensional half-Fourier fast spin-echo MR imaging and a selective inversion-recovery tagging pulse.

OBJECTIVE: The purpose of this study was to evaluate the intraportal blood flow distribution from splenic and superior mesenteric veins with an unenhanced MR angiographic technique using single breath-hold ECG-triggered three-dimensional (3D) half-Fourier fast spin-echo sequence and selective inversion-recovery tagging pulse. SUBJECTS AND METHODS: Seventeen healthy volunteers were included in this prospective study. After obtaining regular single breath-hold ECG-triggered 3D half-Fourier fast spin-echo images without applying a tagging pulse, we placed the selective inversion-recovery tagging pulse on the superior mesenteric vein (TAG-A), the splenic vein (TAG-B), or on both (TAG-C) to study the inflow correlation of tagged or marked blood into the portal vein. MR images were evaluated subjectively by three reviewers. RESULTS: On MR images obtained using the TAG-A pulse to suppress the signal flow from the superior mesenteric vein into the portal vein, the most common pattern of signal loss was observed on the right half of the main portal vein (8/17 subjects). Conversely, on the MR images obtained using the TAG-B pulse, signal loss of the left half of the main portal vein was the most common pattern (11/17 subjects). Signal reduction from the splenic venous flow in the left portal vein was significantly greater than that from the superior mesenteric venous flow (p<0.05). CONCLUSION: The unenhanced MR angiographic technique using single breath-hold ECG-triggered 3D half-Fourier fast spin echo with selective inversion-recovery tagging pulse has the potential to assess the intraportal blood flow distribution from the splenic and superior mesenteric veins.

Adult↗

PubMedDate not supplied

Modified Blalock-Taussig shunt patency for pulmonary atresia: assessment with electron beam CT.

PURPOSE: The purpose of this work was to evaluate electron beam CT (EBCT) for the noninvasive assessment of modified Blalock-Taussig (BT) shunt patency in patients with pulmonary atresia. METHOD: Five infants and children with pulmonary atresia and modified BT shunts underwent contrast-enhanced EBCT. Modified BT shunts from the subclavian artery to the pulmonary artery were performed to improve the pulmonary blood flow. Electrocardiogram (ECG)-triggered EBCT was obtained with a 100 ms exposure, 3 mm section thickness, and 2 mm table feed after intravenous administration of contrast material. Three-dimensional (3D) or maximum intensity projection (MIP) EBCT images were compared with conventional angiography. The visibility of modified BT shunts was graded and recorded with use of a four-point scale. RESULTS: Satisfactory visualization was achieved in both 3D and MIP EBCT images to evaluate modified BT shunt patency. CONCLUSION: Contrast-enhanced 3D or MIP EBCT imaging with ECG trigger may be used as an effective substitute to evaluate modified BT shunts with low radiation dose exposure.

Blood Vessel Prosthesis Implantation↗

PubMedDate not supplied

Hepatic iron deposition on magnetic resonance imaging: correlation with inflammatory activity.

PURPOSES: To define the relation between pathologic inflammatory activity and magnetic resonance imaging (MRI) grades of iron deposition in patients with liver cirrhosis. PATIENTS AND METHODS: In 53 patients with biopsy-proven liver cirrhosis, T2*-weighted gradient echo MRI (echo time > or =6 milliseconds) was reviewed. Grading of parenchymal iron deposition and siderotic nodules in the liver and liver-to-skeletal muscle signal intensity ratios were compared with pathologically defined inflammatory activity. RESULTS: The MRI grade of hepatic siderotic nodules correlated significantly with the grade of periportal inflammation (r = 0.301, P < 0.05) but not with the grade of piecemeal necrosis. The grade of parenchymal iron deposition was not correlated with the grade of periportal inflammation or piecemeal necrosis. There was a nonsignificant trend toward correlation between the histologic grade of hepatic iron content and the grades of periportal inflammation and piecemeal necrosis. CONCLUSION: MRI grading of siderotic nodules correlates with inflammatory activity in cirrhotic patients.

Adult↗

PubMedDate not supplied

MR cholangiopancreatography: comparison of images obtained with 1.0 and 1.5 Tesla units.

OBJECTIVE: To compare the image quality and visualization obtained in MR cholangiopancreatography (MRCP) using different high-field strength (1.0 vs. 1.5 Tesla) MR units and to assess the effect of field strength on MRCP. MATERIALS AND METHODS: This study population included 10 healthy volunteers and 37 patients suspected of having pancreatobiliary diseases. MRCP images were obtained using two MR units with different high-field strengths (1.0 and 1.5 Tesla), with half-Fourier acquisition single-shot turbo spin-echo (HASTE) and rapid acquisition by relaxation enhancement (RARE) sequences. The image quality and visualization of each portion of the pancreatobiliary system were graded and recorded using a four-point scale. Additionally, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured. RESULTS: The SNR and CNR in HASTE sequences acquired with the 1.5 Tesla (T) unit were significantly higher than those acquired with the 1.0 T unit (p=0.001). In qualitative analysis, there were no statistically significant differences in image quality or visualization of the ducts in either HASTE or RARE sequences between 1.0 T and 1.5 T. CONCLUSION: Our study showed that visual image quality provided by MRCP was equivalent at 1.0 and 1.5 T.

Adult↗