Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 919 records · Page 51Linked to original sources

PubMedDate not supplied

Renal arteriovenous malformations: CT features.

The CT and clinical features of six patients with congenital renal arteriovenous malformation (RAVM) were reviewed to determine the characteristics of this condition. The most common symptom was hematuria. The CT images were characterized by masses of vascular density located in the renal sinus and surrounding the pelvicaliceal system with or without dilated renal veins. The exact size of the RAVM and the relation to the pelvicaliceal system were well demonstrated by delayed images or drip infusion technique, whereas the bolus injection technique was essential to document the vascular nature. The potential pitfalls in diagnosis that can occur if only an infusion study is performed are discussed.

Adult↗

PubMedDate not supplied

MRI of primary spleen angiosarcoma with iron accumulation.

A case of splenic angiosarcoma with siderotic nodules is reported. The tumor was hyperechoic on ultrasound and had high density on CT and very low intensity on MR. Gandy-Gamna nodules (siderotic nodules) were demonstrated histopathogically.

Hemangiosarcoma↗

PubMedDate not supplied

MRI of bronchogenic cysts.

The MR appearance of eight bronchogenic cysts is reported. All the cysts appeared homogeneous and were of very high signal intensity, approximating that of CSF on spin-echo T2-weighted imaging, and of relatively high intensity, between that of muscle and subcutaneous fat on T1-weighted imaging. The cysts were round or ovoid and were well demarcated. These findings are consistent with the fluid-containing properties of cysts.

Adipose Tissue↗

PubMedDate not supplied

MRI of primary lymphoma of the liver.

OBJECTIVE: The MR findings in two cases of primary lymphoma of the liver (PLL) are presented. MATERIALS AND METHODS: MR of two cases of primary lymphoma of the liver were reviewed and its features were estimated. RESULTS: Both cases showed a solitary large liver mass. On T1-weighted imaging the tumor was isointense in one and homogeneously hypointense to the liver parenchyma in the other. On T2-weighted imaging both tumors were homogeneously hyperintense. In one case the margin of the tumor was poorly defined, and portal branches were identified within the tumor, an unusual finding in other liver neoplasms. CONCLUSION: In patients with liver masses with homogeneous intensity on MR but without liver dysfunction and other malignancies, PLL should be included in the differential diagnosis.

Aged↗

PubMedDate not supplied

"CT angiogram sign" in obstructive pneumonitis and pneumonia.

OBJECTIVE: The "CT angiogram sign" in dynamic pulmonary CT consists of enhanced branching pulmonary vessels in a homogeneous hypoattenuating consolidation of lung parenchyma and is reportedly useful for diagnosing lobar bronchioloalveolar cell carcinomas. MATERIALS AND METHODS: To identify cases exhibiting the CT angiogram sign, we retrospectively reviewed the reports of 5,500 dynamic incremental CT examinations of the chest. RESULTS: We identified the CT angiogram sign in five patients with obstructive pneumonitis due to lung tumors and four patients with pneumonias. CONCLUSION: The CT angiogram sign can be observed in pulmonary consolidation of varying etiologies.

Adenocarcinoma, Bronchiolo-Alveolar↗

PubMedDate not supplied

Leiomyosarcoma of the kidney: CT and MR appearance.

A case of leiomyosarcoma of the kidney is reported here with its CT and MRI manifestations correlated to the pathologic findings. The leiomyosarcoma appeared as a well-defined multinodular mass of varying density and signal intensity on CT and MRI, respectively. The low signal-intensity regions on T2-weighted MRI exhibited delayed enhancement on CT and contained more fibrous tissues than did other sites that had more spindle-shaped muscle cells. Knowledge of the MR and CT characteristics may permit radiologists to refine the diagnosis of renal leiomyosarcoma considerably.

Female↗

PubMedDate not supplied

MR evaluation of intrapulmonary hematoma.

We report a case of circumscribed intrapulmonary hematoma, in which MR findings were useful in establishing the diagnosis. It is usually easy to make a diagnosis of intrapulmonary hematoma using conventional methods, when clinical history of trauma and regression of the mass can be observed on serial radiography. However, in this case the mass remained almost unchanged 4 months after trauma on chest radiography and CT. Magnetic resonance revealed a hyperintense mass with an even higher signal rim on T1-weighted imaging and an irregular hyperintense mass on T2*-weighted imaging. We made a diagnosis of pulmonary hematoma based on these MR findings. Follow-up chest radiography and CT taken 1 year after the injury, revealed a substantial decrease in the size of the mass, which confirmed the diagnosis. As in this case, some intrapulmonary hematomas regress very slowly or may even increase in size, and diagnosis can be difficult with conventional methods. In such cases, MRI can be helpful.

Adult↗

PubMedDate not supplied

Signal intensity characteristics of mediastinal cystic masses on T1-weighted MRI.

OBJECTIVE: We evaluated the intracystic MR signal intensity of mediastinal cystic masses to identify characteristic intensity patterns according to histologic type. MATERIALS AND METHODS: Magnetic resonance imaging was performed on 26 cystic mediastinal masses consisting of 8 thymic cysts, 5 bronchogenic cysts, 4 pericardial cysts, 5 cystic teratomas, and 4 cystic neurogenic tumors. Signal intensity ratios of each cyst to muscle were calculated on T1-weighted imaging. Surgical records were reviewed to document the presence of intracystic hemorrhage. Chemical analysis of intracystic fluid was performed in three cases. RESULTS: Bronchogenic cysts, cystic teratomas, and cystic neurogenic tumors had relatively high levels of signal intensities. Each pericardial cyst had a lower signal intensity than muscle. The signal intensities of thymic cysts were variable. Intracystic hemorrhage was present in 1 bronchogenic cyst, 2 cystic neurogenic tumors, 4 cystic teratomas, and 3 thymic cysts. No hemorrhage was found in any of the pericardial cysts. Sebaceous fluid was present in 1 cystic teratoma. CONCLUSION: The varying intensities of different cysts were considered to reflect the nature of the intracystic fluid. Since the nature of the fluid can reflect the histology to some extent, T1-weighted MRI will help to differentiate cystic mediastinal masses.

Bronchogenic Cyst↗

PubMedDate not supplied

Inflammatory pseudotumors of the spleen: CT and MRI findings.

OBJECTIVE: Our goal was to elucidate the CT and MRI findings of inflammatory pseudotumors of the spleen. METHODS: The CT and MRI findings of three patients with inflammatory pseudotumors of the spleen were reviewed and compared with the pathologic findings. RESULTS: On the early phase of CT, the masses were hypodense to the normal spleen, and on the delayed phase, they demonstrated delayed enhancement. On T1-weighted MR images, the masses were isointense to the normal spleen, and on T2-weighted images, the masses had heterogeneous low signal intensities. After administration of Gd-DTPA, the masses showed delayed enhancement. CONCLUSION: Inflammatory pseudotumors of the spleen were characterized by low signal intensity on T2-weighted MR images and delayed enhancement after contrast material administration on CT and MRI. The fibrous stroma may contribute to these unusual findings.

Adult↗

PubMedDate not supplied

Computed tomographic findings of Bellini duct carcinoma of the kidney.

OBJECTIVE: To analyze CT findings of Bellini duct carcinoma, a rare variant of renal cell carcinoma. MATERIALS AND METHODS: The CT findings of five cases of Bellini duct carcinoma were reviewed and the findings were recorded. RESULTS: In all cases the affected kidneys maintained the normal outer contours. In four cases the renal masses protruded into the central sinuses. Contrast enhancement was minimal in four cases. CONCLUSION: Bellini duct carcinoma should be suspected in cases with these CT findings.

Adult↗

PubMedDate not supplied

Helical CT imaging of bronchial arteries with curved reformation technique in comparison with selective bronchial arteriography: preliminary report.

PURPOSE: Our goal was to evaluate the ability of helical CT to identify and demonstrate the origins and courses of bronchial arteries, using the curved reformation technique, in patients undergoing bronchial arterial interventional procedures. METHODS: Thin section helical CT was performed on seven patients before bronchial arterial interventional procedures. The curved reformation technique was used to demonstrate the origins and continuous vessel tracing of bronchial arteries and compared with bronchial arteriographic findings. RESULTS: In all, 16 bronchial arteries were evaluated, 8 on the right and 8 on the left. The origins of 12 bronchial arteries were identified. In the demonstration of tracing vessels, seven right bronchial arteries and three left were classified as excellent or fair. CONCLUSION: Helical CT imaging with the curved reformation technique is helpful in identifying bronchial arteries, especially on the right, in patients with indications for bronchial arterial interventional procedures.

Adult↗

PubMedDate not supplied

Efficacy of helical CT in T-staging of gastric cancer.

PURPOSE: The purpose of this study was to evaluate the performance of helical CT in preoperative T-staging in patients with gastric cancer. METHOD: A total of 71 patients with an established diagnosis of gastric cancer [75 lesions, 46 early (T1) and 29 advanced (T2 or more) cancers] were evaluated with helical CT. Helical CT was performed with 5-mm slice thickness at 5-mm/s table incrementation. Using the volumetric data by helical scanning, axial CT images (5-mm slice thickness at 5-mm intervals) and multiplanar reconstruction (MPR) images were obtained. CT findings were compared with histopathologic studies of the resected specimen. RESULTS: Sensitivity of helical CT for gastric cancer was 26% (12 of 46) for early and 100% (29 of 29) for advanced cancer. Three lesions were misdiagnosed as gastric cancer by helical CT. Histopathologically, all early gastric cancers detected by helical CT were either polypoid or elevated types or showed massive invasion of the submucosal layer. The differentiation between T1 cancer with massive submucosal invasion and advanced cancer was difficult. The differentiation between T2 and T3 cancer was possible in 73% (19 of 26) and between T1/T2 and T3/T4 (extraserosal invasion) in 83% (34 of 41). Overall T-staging was correct in 66% (27 of 41). MPR images improved the detection rate (three lesions) or increased confidence in T-staging (eight lesions) over axial CT images. CONCLUSION: When helical CT detected gastric cancer that was not a polypoid or elevated type with underlying normal-appearing gastric wall, it was either T1 cancer with massive invasion of the cancer cells into the submucosal layer or advanced cancer. However, differentiation between these two stages was difficult on CT. Diagnosis of serosal invasion was not markedly improved by helical CT. MPR images increased confidence in the staging of certain gastric cancers, such as those in locations where CT images are susceptible to partial volume averaging effects.

Adult↗

PubMedDate not supplied

Patterns of peripheral enhancement in breast masses: correlation of findings on contrast medium enhanced MRI with histologic features and tumor angiogenesis.

PURPOSE: Our goal was to review patterns of peripheral enhancement on contrast-enhanced MRI of the breast and to correlate radiologic findings with pathologic features. METHOD: We reviewed the MR images of 124 consecutive women with breast lesions. Peripheral enhancement was identified in 35 (32 malignant, 3 benign) lesions. MRI findings were correlated with pathologic features including microvessel density and distribution determined histologically. RESULTS: Early peripheral enhancement with centripetal progression was seen in invasive carcinomas with a high peripheral and a low central microvessel density, associated with fibrosis and/or necrosis (n = 18; 15 with central fibrosis, 2 with fibrosis and necrosis, and 1 with necrosis alone). Early peripheral enhancement with minimal or no change in enhancement was seen in both malignant (n = 10) and benign (n = 3) lesions. Delayed peripheral enhancement with centrifugal progression was seen in carcinomas that had an expansive growth pattern and a high marginal vessel density with or without a vascularized rim of connective tissue (n = 4). CONCLUSION: Early peripheral enhancement with centripetal progression appears to be fairly specific for carcinomas, whereas early enhancement with minimal or no centripetal progression, although more common in malignant tumors, may be seen in some benign lesions as well.

Adult↗

PubMedDate not supplied

Bronchogenic carcinoma invasion of the chest wall: evaluation with dynamic cine MRI during breathing.

PURPOSE: Our goal was to assess the utility of breathing dynamic cine MR (BDCMR) in the evaluation of tumor invasion to the chest wall in bronchogenic carcinomas. METHOD: BDCMR imaging was performed preoperatively in 25 patients with bronchogenic carcinomas adjacent to the chest wall. Twelve sequential images were obtained in the same coronal and/or sagittal planes during one respiratory cycle with fast spoiled GRASS sequence, and analysis with cine-loop display was performed. RESULTS: In all 14 cases in which free movement of tumor along the parietal pleura on BDCMR was demonstrated, no chest wall invasion was evident at thoracotomy. However, of 11 patients with fixation of the tumor on BDCMR, 5 had benign pleural adhesions, 5 had chest wall invasion at thoracotomy, and 1 with an apical tumor had no benign pleural adhesion or chest wall invasion. CONCLUSION: Although BDCMR cannot distinguish benign pleural adhesions from chest wall invasion by tumor, this method accurately estimated the free movement of lung tumors with no invasion of chest wall from bronchogenic carcinomas prior to surgery.

Aged↗

PubMedDate not supplied

MRI of groove pancreatitis.

PURPOSE: The purpose of this work is to describe the findings on MRI in patients with groove pancreatitis, a specific form of chronic pancreatitis affecting the groove between the pancreatic head, the duodenum, and the common bile duct. METHOD: MR images, including MR cholangiopancreatography, of five patients with groove pancreatitis were reviewed. Three patients underwent pancreatoduodenectomy due to serve duodenal stenosis, and the MR findings were compared to the histologic findings. RESULTS: A sheet-like mass was demonstrated between the pancreatic head and the duodenum in all patients. The masses were hypointense relative to pancreatic parenchyma on T1-weighted images and iso- to slightly hyperintense on T2-weighted images. After administration of Gd-DTPA, the masses showed delayed enhancement. Histologically, fibrous scar tissue was detected in the groove. CONCLUSION: MR images can clearly demonstrate the fibrous tissue in the groove in groove pancreatitis, and MR cholangiopancreatography can also provide useful information.

Adult↗

PubMedDate not supplied

Hepatic angiomyolipoma: report of changing size and internal composition on follow-up examination in two cases.

We present two cases of hepatic angiomyolipoma in which the size and internal composition of the tumor changed during the course of follow-up study. The tissue elements composing the tumor are thought to grow or regress independently during the disease's clinical course. Radiologists should be aware that hepatic angiomyolipoma can change in size and internal composition during its natural course.

Adult↗

PubMedDate not supplied

Radiologic features of intrahepatic bile duct adenoma: a look at the surface of the liver.

We report the radiological features of intrahepatic bile duct adenoma (BDA) in three patients. BDA was shown as a small mass located in the peripheral region of the liver with each imaging modality: a hypervascular mass on angiography and a mass appearing as early nodular enhancement found disproportionately evident compared with their small size and distinct delayed or prolonged enhancement on CT. BDA should be included in the diseases to be differentiated from hypervascular hepatic tumors.

Adenoma↗

PubMedDate not supplied

"Crazy paving appearance" on high resolution CT in various diseases.

PURPOSE: The purpose of this work was to demonstrate the variety of causes of crazy-paving appearance (CPA) on high resolution CT (HRCT). METHOD: To identify cases exhibiting CPA (ground-glass opacity with superimposed interlobular septal thickening and intralobular interstitial thickening) on HRCT, we prospectively searched for them over a period of 29 months. RESULTS: We identified 10 cases of CPA on HRCT, including 4 Pneumocystis carinii pneumonia, 1 alveolar proteinosis, 1 usual interstitial pneumonia, 1 pulmonary hemorrhage, 1 acute radiation pneumonitis, 1 adult respiratory distress syndrome, and 1 drug-induced pneumonitis. CONCLUSION: CPA can result from a variety of diseases. When we encounter CPA on HRCT, clinical information is necessary for differentiation of these entities.

Adolescent↗