Ichiro Ogata

Radiological presentations of Castleman's disease.

The radiographic appearances of three cases of Castlemans disease of hyaline vascular type are reported. CT demonstrated homogeneous masses with marked contrast enhancement. Calcification was seen in one, and associated lymphadenopathy was seen in two. All tumors were hypervascular with prominent tumor blush on angiography. Sonography showed the masses to be hypoechoic with hyperechoic spots. On MR imaging, all tumors had homogeneous architecture with hypointensity on T1-weighted images and hyperintensity on T2-weighted images. In tumors with above characteristics in areas where lymphoid tissue is normally found, Castlemans disease should be added to the list of differential diagnosis.

Balloon-occluded retrograde transvenous embolization of a pelvic arteriovenous malformation

We successfully performed embolization therapy for a pelvic arteriovenous malformation by the retrograde transvenous approach using a liquid embolie material. This malformation was unique in that it had a single draining vein, which allowed this technique employing an occlusion balloon.

Spiral CT of the pancreas: The value of small field-of-view targeted reconstruction

Purpose: to compare the value of a retrospective targeted high-resolution spiral CT to the standard reconstruction technique in the assessment of pancreatic diseases Material and Methods: Spiral CT pancreatic images of a standard-size reconstruction protocol were compared prospectively with those of a retrospective targeted high-spatial-resolution reconstruction protocol in 30 patients. Prior to clinical evaluation, a phantom study was performed to evaluate the spatial resolution and signal-to-noise ratio of both protocols Results: the high-resolution protocol achieved a good signal-to-noise ratio with acceptable spatial resolution. Phantom studies revealed increased image noise (+17%) with an increase in spatial resolution (+100%). in patients studied with the high-resolution protocol, the increase in noise was not significant but there was a marked improvement in the definition of small details Conclusion: Images obtained with a targeted high-spatial-resolution reconstruction protocol showed superior lesion definition and vascular opacification compared with those obtained with a standard-size reconstruction protocol. This technique may have potential in the evaluation of small pancreatic abnormalities

Pitfalls in image reconstruction of helical CT angiography: an experimental study.

This study was undertaken to evaluate the effects of the object related factors: background tissue and the direction of vessels on the morphological reproducibility of helical CT angiography. Cylindrical tubes filled with a diluted contrast medium were prepared to obtain vascular phantoms. The scan was performed within various background tissues. For the evaluation of the direction of the vessels, two types of vascular phantoms were prepared. The phantoms were scanned by varying beam collimations and scan pitches. Reconstructed CT images were markedly affected by the background tissue. The reconstructed images were also affected by the direction of vessels.

Spiral CT of the pancreas

Purpose: to compare the value of a retrospective targeted high-resolution spiral CT to the standard reconstruction technique in the assessment of pancreatic diseasesMaterial and Methods: Spiral CT pancreatic images of a standard-size reconstruction protocol were compared prospectively with those of a retrospective targeted high-spatial-resolution reconstruction protocol in 30 patients. Prior to clinical evaluation, a phantom study was performed to evaluate the spatial resolution and signal-to-noise ratio of both protocolsResults: the high-resolution protocol achieved a good signal-to-noise ratio with acceptable spatial resolution. Phantom studies revealed increased image noise (+17%) with an increase in spatial resolution (+100%). in patients studied with the high-resolution protocol, the increase in noise was not significant but there was a marked improvement in the definition of small detailsConclusion: Images obtained with a targeted high-spatial-resolution reconstruction protocol showed superior lesio...

Hepatic parenchymal perfusion abnormalities after pancreaticobiliary surgery. Evaluation with dynamic helical CT.

Purpose: To evaluate perfusion abnormalities of the liver after pancreaticobiliary surgery Material and Methods: We retrospectively evaluated 128 patients with pancreaticobiliary malignant tumors who had been examined both before and after surgery by means of helical CT of the liver. An infusion of 3 ml/s of 60% nonionic contrast material was followed by helical CT of the liver in a sequential arterial phase, portal venous phase, and equilibrium phase Results: of 128 patients, we followed 97. In 21 patients (22%) we found 47 lesions with perfusion abnormalities that were detected 1–33 months (mean 6.6 months) after the operation. All patients were asymptomatic. The shape of each perfusion abnormality was characterized as geographic (n=23, 47%), wedgeshaped (n=21, 45%), or round (n=3, 83.8%). The abnormalities were seen in the arterial phase in 46 lesions (98%), in the portal venous phase in 18 lesions (38%), and in the equilibrium phase in 1 lesion (0.2%). In all lesions, the size either decreased spontaneously, or it remained unchanged for more than one year Conclusion: Perfusion abnormalities of the liver may occur in patients who undergo pancreaticobiliary surgery. This findings should not be confused with hypervascular metastases