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Biomedical subjects

Y Itai

Publications and source records attributed to Y Itai.

At least 361 records · Page 20Linked to original sources
PubMedDate not supplied

Improved detection of small insulinomas with intravenous dynamic CT.

OBJECTIVE: To evaluate the usefulness of intravenous dynamic CT in demonstrating angiographically negative insulinomas. MATERIALS AND METHODS: Two patients with endocrinologic evidence of insulinoma were examined with intravenous bolus-dynamic CT. RESULTS: Angiographically negative insulinomas as small as 5-7 mm were demonstrated unequivocally as enhancing nodules. CONCLUSION: Intravenous dynamic CT using larger amounts of contrast material can improve detection of small (< 1.0 cm) insulinomas.

Adult↗
PubMedDate not supplied

Focused radiation hepatitis after Bragg-peak proton therapy for hepatocellular carcinoma: CT findings.

Radiation hepatitis is clearly demonstrated by noncontrast and contrast enhanced CT following radiotherapy for liver diseases. Radiation hepatitis is dependent on dose distribution and is usually demonstrated as a non-segmental bandlike lesion after photon therapy. We report a case of focused, oval-shaped radiation hepatitis that was induced by photon therapy. The attenuation difference was localized in a high-dose area caused by Bragg-peak proton therapy.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Magnetization transfer contrast imaging of the cervical spine at 0.3 T.

OBJECTIVE: We assessed the efficacy of magnetization transfer contrast (MTC) imaging of the cervical spine in conjunction with a gradient recalled echo (GRE) technique using a 0.3 T permanent magnet imager. MATERIALS AND METHODS: Seventy patients were prospectively investigated. Multislice sagittal and axial images of the cervical spine with and without MTC were obtained using a GRE sequence (TR/TE/flip angle = 750 ms/23 ms/25 degrees). The contrast-to-noise ratios (C/Ns) for CSF versus cord or disk were calculated for quantitative analysis. Qualitative image analysis was also performed. RESULTS: Both sagittal and axial MTC images had significantly higher C/N values than conventional GRE images. The MTC images showed better differentiation between the CSF and the cord or thecal sac as well as better delineation of the nerve roots. Furthermore, MTC images demonstrated syringomyelia more clearly than conventional images. CONCLUSION: Magnetization transfer contrast images at 0.3 T are effective for diagnosing diseases of the cervical spine.

Adolescent↗
PubMedDate not supplied

Segmented areas of increased attenuation in the liver caused by right adrenal tumors: CT features.

OBJECTIVE: Our goal was to describe attenuation differences bordered by a straight line in the right hepatic lobe on enhanced CT in patients with right adrenal tumors and to discuss the cause of this appearance. MATERIALS AND METHODS: Three patients showing attenuation differences bordered by a straight line were discovered in the CT files of 26 cases of right adrenal tumor over 3 cm in diameter. All CT scans were examined by incremental dynamic study. RESULTS: Two patients had large zone of hyperattenuation in the right lobe bordered with a straight line intersecting both anterior branches of the right portal vein and the inferior vena cava (IVC). A third patient and one of the two patients mentioned already had zones of relative hyper- and hypoattenuation in the medial portion of the posterior hepatic segment, respectively. All three patients had large right adrenal tumors, which severely compressed the right hepatic vein near its confluence with the IVC and/or the IVC in or below its intrahepatic portion. The distribution of attenuation differences was similar to the hyperattenuation at CT arteriography or perfusion defect at CT arterial portography under temporary balloon occlusion of the right hepatic vein and inferior right hepatic vein, respectively. CONCLUSION: Straight-bordered attenuation differences within the right hepatic lobe at dynamic CT can be caused by compression of the right hepatic vein by large right adrenal tumors.

Adolescent↗
PubMedDate not supplied

Knee extension and flexion: MR delineation of normal and torn anterior cruciate ligaments.

OBJECTIVE: Our goal was to assess the effect of joint position of semiflexed and extended knees in MR delineation of the anterior cruciate ligament (ACL). METHODS: With a mobile knee brace and a flexible surface coil, the knee joint was either fully extended or bent to a semiflexed position (average 45 degrees of flexion) within the magnet bore. Sets of oblique sagittal MR images were obtained for both extended and flexed knee positions. Thirty-two knees with intact ACLs and 43 knees with arthroscopically proven ACL tears were evaluated. Two observers compared paired MR images of both extended and flexed positions and rated them by a relative three point scale. Anatomic correlation in MR images was obtained by a cadaveric knee with incremental flexion. RESULTS: The MR images of flexed knees were more useful than of extended knees in 53% of the case reviews of femoral attachments and 36% of reviews of midportions of normal ACLs. Compared with knee extensions, the MR images for knee flexion provided better clarity in 48% of reviews of disrupted sites and 52% of residual bundles of torn ACLs. Normal ACL appeared taut in the knee extension and lax in semiflexion. CONCLUSION: Compared with MR images of knees in extension, MR images of knees in flexion more clearly delineate the femoral side of the ligament with wider space under the intercondylar roof and with decreased volume-averaging artifacts, providing superior visualization of normal and torn ACLs.

Adolescent↗
PubMedDate not supplied

CT of the medial umbilical folds.

PURPOSE: The goal of our study was to investigate the appearance of the medial umbilical folds on CT. METHOD: We retrospectively reviewed the CT images of 30 consecutive patients with massive ascites. In addition, we inspected the inner pelvic wall in cadavers. RESULTS: The medial umbilical folds were well recognized on CT in 21 of 30 patients, bilaterally in 20 and unilaterally in 1. In four patients the folds were undetectable after the ascites resolved. The CT findings were supported by those studied in cadavers, in which the folds were recognized as a peritoneal reflection in 13 of 20. CONCLUSION: We concluded that medial umbilical folds could be commonly visualized on CT when ascites was present.

Administration, Oral↗
PubMedDate not supplied

Von Meyenburg complexes of the liver: imaging findings.

PURPOSE: Our purpose was to present imaging findings of six cases proven or supposed to be von Meyenburg complexes (VMCs) with a basis of reviewing the pathologic literature and to describe imaging points for the diagnosis of typical VMC along with its differential diagnosis. METHOD: Six cases were diagnosed as VMC of the liver with imaging modalities (one had histopathologic proof). Both ultrasound (US) and CT were available for all cases, and MRI was used for three cases. Follow-up with US, CT and/or MRI was performed in five cases. RESULTS: US detected varying abnormalities of the livers in four cases. CT and MRI revealed multiple or numerous intrahepatic tiny (usually < 5 mm) cystoid lesions in all of the cases. The lesions were scattered throughout the livers, and some of them were located more frequently adjacent to the medium-sized portal veins than to the hepatic veins of similar size on CT. Moreover, some lesions were apparently located in the subcapsular areas (up to the hepatic capsules). They were usually irregular in shape and showed no enhancement but increased in number by approximately 80-150% after administration of intravenous contrast medium. The T2-weighted MR images and MR cholangiopancreatography showed the lesions to be much more apparent and to be more numerous than T1-weighted images did. Follow-up of five cases with imaging modalities did not show remarkable change of the lesions. CONCLUSION: Despite our limited experience, VMC lesions seem to show some CT and MR features different from those of other multiple small hepatic lesions. They presented as multiple or numerous intrahepatic tiny cystoid lesions usually with irregular contour, scattered throughout the liver up to the subcapsular areas, and were detected in far greater number by enhanced CT or T2-weighted MR images than by unenhanced CT or T1-weighted images. They showed no remarkable change on long term follow-up imaging. We propose that a diagnosis of typical VMC could be made after analyzing CT or MR images carefully with good understanding of its pathologic basis, but imaging follow-up is necessary in oncology patients.

Aged↗
PubMedDate not supplied

MRI of mucosal malignant melanoma of the head and neck.

PURPOSE: The objective of this study was to determine the characteristic MR findings for mucosal malignant melanomas of the head and neck. METHOD: We retrospectively analyzed the MR images for six patients with this entity. T1-weighted SE images with and without gadolinium and T2-weighted fast SE images were obtained. MR images were analyzed qualitatively and quantitatively by comparing the signal intensity of the melanoma with that of muscle. RESULTS: On T1-weighted images, five melanomas were hyperintense and one was isointense. On T2-weighted images, five were of mixed intensity and one showed isointensity. The mean signal intensity ratio of the primary melanoma to muscle was 1.51 and 1.39 on T1-weighted images with and without gadolinium, respectively. These values were not statistically significant. CONCLUSION: Hyperintensity on T1-weighted images is characteristic of this entity, but not universal.

Adipose Tissue↗
PubMedDate not supplied

Testicular feminization: role of MRI in diagnosing this rare male pseudohermaphroditism.

PURPOSE: The purpose of our study was to assess the role of MR in the diagnosis and follow-up of patients with testicular feminization (TF). METHOD: MR scans of seven patients with TF were retrospectively reviewed. RESULTS: MR could diagnose uterus agenesis in all cases. Undescended testes were depicted within or just below the inguinal canal in four cases. They were smaller and more hypointense than those in normal males. Testes that we could not find by MR were found during surgery in two cases. They were just below the inguinal canal where we had not scanned caudally enough in one and they were too small to be detected in the other. CONCLUSION: MR can demonstrate both uterine agenesis and undescended testes in TF. The latter tend to be missed because they are small and can be anywhere in the abdomen and inguinal canal. Radiologists should perform careful MR examination to detect testes in patients suspected having TF, as these organs are more likely to undergo malignant neoplasia.

Adolescent↗
PubMedDate not supplied

CT evaluation of hepatic injury following proton beam irradiation: appearance, enhancement, and 3D size reduction pattern.

PURPOSE: The purpose of this study was to investigate the long-term imaging appearances of hepatic injury following proton beam irradiation. The time-attenuation curves, time of appearance and recovery, and 3D size reduction pattern are described in patients of different ages and genders with different irradiation doses, irradiated portals, and Child groups. METHOD: Forty-six patients with hepatocellular carcinoma underwent 50 to 84 Gy proton beam irradiation in periods of 14-52 days. CT including noncontrast and dynamic study was performed every 3 months starting 3 weeks after the end of irradiation. The 3D volume measurement of areas of radiation-induced hepatic injury was performed through incremental dynamic CT images in every follow-up study. CT follow-up study of the patients was done for 12-76 months. RESULTS: Radiation-induced hepatic injury was observed as low attenuation areas on noncontrast CT and enhanced areas on dynamic study in the regions corresponding to the irradiation portals. Of our cases, 67.5% showed the appearance of radiation hepatitis in 3-4 weeks and 95.3% in 3-4 months after the end of irradiation. In both periods, there was a significant delay in the female patients. The time-attenuation curve showed an early and prolonged enhancement of the irradiated regions. The volume reduction pattern of the injured areas was found to be longstanding, exponential, and directed from periphery to the center. CONCLUSION: Early appearance of radiation-induced hepatic injury was found only to be gender dependent, with a tendency to occur with higher irradiated doses; no other parameters affected this phenomenon in our cases. Disappearance of the injured areas, if present, takes a long time (at least 42 months).

Adult↗
PubMedDate not supplied

Early radiation effects on the liver demonstrated on superparamegnetic iron oxide-enhanced T1-weighted MRI.

Early radiation-induced liver injury during radiotherapy detected by a particulate reticuloendothelial MR contrast agent (superparamagnetic iron oxide; SPIO) is described in a patient with cholangiocarcinoma. The irradiated hepatic parenchyma appeared as a heterogeneous, less decreased signal intensity area than the nonirradiated area on MR images after SPIO administration. Resultant differences in signal intensity were better visualized on SPIO-enhanced T1-weighted images than SPIO-enhanced T2-weighted images, although SPIO-enhanced T2*-weighted fast field echo imaging was the most sensitive.

Contrast Media↗
PubMedDate not supplied

Reevaluation of spiral CT cholangiography: basic considerations and reliability for detecting choledocholithiasis in 80 patients.

PURPOSE: The purpose of this work was to reevaluate the characteristics and diagnostic accuracy of spiral CT cholangiography (CTC) for detecting biliary calculi. METHOD: Spiral CTC was performed in 133 patients with suspected biliary or pancreatic diseases. All source images were reviewed by two radiologists who were unaware of final diagnoses. Attenuation values of bile were correlated with biochemical data and visualization of anatomic detail. The statistical measures in detecting the presence of choledocholithiasis were calculated in 80 patients with confirmed diagnoses. RESULTS: Statistically significant correlations were found between the degree of biliary enhancement and both serum bilirubin and alkaline phosphatase levels. Of the 80 patients, 18 (23%) had choledocholithiasis and 62 did not. Observers diagnosed them with a sensitivity of 89% and a specificity of 98%. A mild adverse reaction to contrast material was observed in three (2.3%) patients. CONCLUSION: Spiral CTC is a reliable, noninvasive, and accessible technique for detecting choledocholithiasis.

Adult↗
PubMedDate not supplied

Intrahepatic portosystemic venous shunts: spectrum of CT findings in external and internal subtypes.

PURPOSE: The purpose of this work was to survey the spectrum of CT findings in intrahepatic portosystemic venous shunts (IPSVSs). METHOD: One thousand consecutive liver CT scans examined with an enhanced helical technique were retrospectively reviewed on workstation to find IPSVSs. RESULTS: IPSVSs were noted in 37 patients and divided into two subtypes according to the location of the communicating systemic vein, either outside (external type, n = 34) or within (n = 4) the liver (one patient had both internal and external types). All the external-type shunts were noted in cases with portal hypertension (n = 34). Most shunts (n = 30) ran through segment 4 and/or 3 and came out near the falciform ligament, but five shunts were noted in segment 2 communicating either with the systemic vein (n = 3) or probably with an enlarged left gastric vein (n = 2). Solitary portohepatic venous shunts (internal type) were noted in three cases with (n = 2) or without (n = 1) aneurysmal dilatation and many portohepatic venous shunts in another patient. CONCLUSION: IPSVSs of the external type were far common than those of the internal type, always associated with increased pressure of the portal system and in specific sites probably lacking the hepatic capsule.

Adult↗
PubMedDate not supplied

MR imaging of Pellegrini-Stieda disease.

OBJECTIVE: To describe the MR imaging of Pellegrini-Stieda disease, a post-traumatic ossification of the medial collateral ligament with typical radiographic findings. METHODS: Coronal and/or axial T2*-weighted field echo and T1-weighted conventional spin echo MR images were obtained with 1.5-Tesla or 0.5-Tesla units. Four patients with radiographic and clinical diagnoses of Pellegrini-Stieda disease were examined. Surgery was performed on one patient, and histopathologic correlation was obtained. RESULTS AND CONCLUSION: Delineating it as a signal void, T2*-weighted MR imaging indicated the precise extent of the osseous fragment in relation to the medial collateral ligament. T1-weighted imaging showed the presence of fatty marrow as a high signal region within the fragment, indicating maturity of the fragment. These findings may help to determine preoperative planning for resection of massive fragments around the ligament. Pellegrini-Stieda disease cannot be considered rare, since it is often encountered in daily MRI examinations.

Adult↗
PubMedDate not supplied

Fibrous scar in the infrapatellar fat pad after arthroscopy: MR imaging.

PURPOSE: We describe the MR appearance of fibrous scars in the infrapatellar fat pad after arthroscopy. MATERIALS AND METHODS: The subjects were 96 patients who underwent arthroscope-assisted anterior cruciate ligament (ACL) reconstruction and were examined by oblique sagittal MR imaging at different follow-up intervals. Two observers evaluated the characteristics of the fibrous scars in the infrapatellar fat pad. RESULTS: All fibrous scars with low signal intensity were accentuated at the portal and coursed horizontally through the infrapatellar fat pad. The fibrous scar within the fat pad occurred and peaked within 6 months after arthroscopy. It then subsided gradually and had disappeared by one year later in nearly half of the patients. CONCLUSION: Identifying MR imaging characteristics of fibrous scars in the fat pad after arthroscopy may be clinically helpful to differentiate these scars from other abnormalities that involve the infrapatellar fat pad.

Adipose Tissue↗
PubMedDate not supplied

Utility of serum CA 19-9 monitoring in preoperative radiotherapy for pancreatic cancer.

BACKGROUND/AIMS: Pancreatic cancer is extremely refractory even to aggressive treatments including surgery, resulting in early metastasis and/or local recurrence. We investigated changes in serum tumor marker CA 19-9 levels during preoperative radiotherapy in conjunction with initial treatment failure. METHODOLOGY: Twenty-three patients presenting with localized disease and an increased serum CA 19-9 level, who were slated to undergo pancreatectomy and/or intraoperative radiotherapy following preoperative radiotherapy were reviewed. CA 19-9 response, the ratio of post-radiotherapy level before laparotomy to pre-radiotherapy level, was analyzed in relation to disease-control time and survival. RESULTS: Eleven patients revealed metastasis at restaging or laparotomy; 12 patients (52%) completed aggressive treatments. Initial failure was identified at the liver (52%), peritoneum (52%), or local site (26%) with a median disease-control time of 91 days; 7 patients showed combined failure. All but 1 patient died of cancer with a median survival time of 264 days. CA 19-9 response (range: 0-1185%) did not correlate with disease-control time or survival; 8 progressive-disease patients (> 140% response), however, showed significantly shorter disease-control time than 15 nonprogressive-disease patients (< or = 140% response). CONCLUSIONS: CA 19-9 monitoring is useful in preoperative radiotherapy for identifying patients who will not benefit by succeeding aggressive treatments by predicting early metastasis.

Adult↗