Biomedical subjects

K Ohtomo

Publications and source records attributed to K Ohtomo.

At least 109 records · Page 6Linked to original sources

PubMed1994

[Usefulness of superparamagnetic iron oxide particle (AMI-25) enhanced MR imaging for the diagnosis of liver tumors: comparison with contrast enhanced CT].

The purpose of this study was to clarify the usefulness of SPIO-enhanced MRI in the diagnosis of liver tumors in comparison with contrast-enhanced CT. The subjects were forty patients with 154 nodules in the liver. We compared SPIO-enhanced MRI with contrast-enhanced CT in terms of tumor-liver contrast and detectability of liver tumors. In terms of tumor liver contrast, SPIO-enhanced MRI was equal or superior to contrast-enhanced CT in 82% of cases. In the detectability of liver tumor, SPIO-enhanced MRI detected more tumors than contrast-enhanced CT, especially small tumors. Tumors undetected by SPIO-enhanced MRI that were detected by contrast-enhanced CT and/or plain MRI were adenomatous hyperplasia and inflammatory pseudotumor according to fine needle biopsy. There were no severe complications of SPIO-enhanced MRI. In conclusion, SPIO-enhanced MRI will be more useful than contrast-enhanced CT in the diagnosis of liver tumors. SPIO-enhanced MRI may be a promising diagnostic method for the detection of hepatic tumors, especially small ones.

Adult↗

PubMed1994

[Distinction between adrenal adenomas and metastases using 0.5 Telsa MR imaging: diagnosis with out-of-phase T2*-weighted gradient-field-echo image].

The purpose of this study was to investigate the ability of MR imaging with a 0.5-T apparatus to distinguish adrenal adenomas from adrenal metastases. The series included 23 adrenal adenomas (18 non-hyperfunctioning adenomas, 5 hyperfunctioning) and 23 adrenal metastases (14 from lung, 5 liver, 3 colon, and 1 stomach cancer). The signal intensity (SI) ratio (adrenal tumor/liver) on T1-, T2-, and T2*-weighted MR images was calculated for adrenal tissue characterization. Adrenal adenomas were more precisely distinguished from adrenal metastases on T2*-weighted images (21/23, 91%) than on T2-weighted images (15/23, 65%). In conclusion, T2*-weighted images were better than routine T2-weighted images in distinguishing adrenal adenomas from adrenal metastases. The reason could be that the total signal intensity of adrenal adenomas which contained some fat components decreased on T2*-weighted images due to an out-of-phase effect.

Adenoma↗

PubMed1994

Large scale clinical evaluation of bowel contrast agent containing ferric ammonium citrate in MRI.

Clear identification of bowel has been thought to be essential in diagnosis by abdominal MRI. We have completed the clinical phase III trial of a new oral contrast agent (FerriSeltz) which is a ferric ammonium citrate based bowel contrast agent. FerriSeltz is a powder that is dissolved in 300 ml water to create a grape-flavored effervescent drink. We have evaluated the usefulness of FerriSeltz, and compared groups receiving 600 mg and 1200 mg of ferric ammonium citrate, the use and nonuse of parasympathetic blockers, and patients with and without fasting in 174 patients who underwent abdominal MRI using this agent. FerriSeltz was found to brighten the stomach and duodenum, contribute to the improvement in diagnostic efficacy, be safe as a bowel contrast agent in abdominal MRI, and be associated with an extremely low incidence of side effects (only mild diarrhea in one of 169 patients). No significant differences were found in the contribution to the improvement in diagnostic efficacy between the two dosage groups, the use and nonuse of parasympathetic blockers, or patients with and without fasting. We concluded that ferric ammonium citrate based compound (FerriSeltz) is a promising bowel contrast agent in abdominal MRI.

Abdominal Neoplasms↗

PubMed1994

Abdominal wall desmoid mimicking intra-abdominal mass: MR features.

A case of abdominal wall desmoid which enlarged toward the liver and mimicked an intra-abdominal tumor is presented. T*2-weighted MR images clearly demonstrated the tumor's continuity with the rectus abdominis muscle. The case presented suggests MRI may provide more valuable information concerning the origin of a right-upper-quadrant mass than CT does. However, the nature of the signals and attachment which this case showed were so unusual for desmoids that this case has not been diagnosed accurately.

Abdominal Muscles↗

PubMed1994

Radiofrequency thermal balloon coronary angioplasty: a new device for successful percutaneous transluminal coronary angioplasty.

OBJECTIVES: The purpose of this study was to evaluate the effects of thermal balloon percutaneous transluminal coronary angioplasty using radiofrequency energy in the treatment of patients with failed coronary angioplasty and complex lesions. In addition, we evaluated restenosis after radiofrequency thermal balloon applications. BACKGROUND: The efficacy of coronary angioplasty is limited by the relatively low success rate in complex lesions and the high frequency of restenosis. Few reports have studied the combined effects of pressure and laser thermal energy. This study describes a new device for coronary angioplasty using radiofrequency thermal energy. METHODS: Thirty-two patients with failed conventional coronary angioplasty or complex lesions were treated with radiofrequency thermal balloon coronary angioplasty. Radiofrequency energy was delivered up to 11 times in exposures ranging from 30 to 60 s in duration. This combined effect allowed the vascular wall to be heated to temperatures ranging from 60 to 70 degrees C. Follow-up coronary angiography was performed, on average, 6 months after the procedure. RESULTS: Successful radiofrequency coronary angioplasty was achieved in 28 (82%) of 34 lesions. There was one abrupt coronary artery occlusion (3%) and no death, perforation or dissection. Angiographic restenosis occurred in 14 (56%) of 25 lesions. CONCLUSIONS: In patients with failed coronary angioplasty and difficult complex lesions, radiofrequency coronary angioplasty could potentially improve angioplasty success rates and may have important implications for bailout cases with abrupt occlusion. However, restenosis remains a significant problem.

Angioplasty, Balloon, Coronary↗

PubMed1994

Adrenal adenomas: characteristic hyperintense rim sign on fat-saturated spin-echo MR images.

PURPOSE: To determine whether adrenal adenomas can be differentiated from metastases on fat-saturated magnetic resonance (MR) images. MATERIALS AND METHODS: Twenty-eight adrenal adenomas and 20 metastatic lesions were imaged at 1.5 T by means of fat-saturated T1- and T2-weighted and gadolinium-enhanced T1-weighted sequences. The authors evaluated visually whether structures of high signal intensity (hyperintense rim sign) could be observed in the outer margin of the adrenal masses. RESULTS: Twenty-six of 28 adrenal adenomas revealed the hyperintense rim sign on at least one kind of fat-saturated image, compared with only one of 20 metastases. The sensitivity of the hyperintense rim sign as suggestive of adrenal adenoma was 92%, specificity was 95%, and overall accuracy was 94%. CONCLUSION: The hyperintense rim sign is characteristic of adrenal adenomas. Thus, adrenal adenomas can be differentiated from metastases by means of this new imaging sign on fat-saturated MR images.

Adrenal Cortex Neoplasms↗

PubMed1994

Localization of copper to afferent terminals in rat locus ceruleus, in contrast to mitochondrial copper in cerebellum.

We examined copper localization in the locus ceruleus and cerebellum of rat brain by Timm's sulfide-silver staining, as modified by Danscher. Dense silver particles revealing copper localization were observed in sections of the locus ceruleus and cerebellum after pre-treatment with trichloroacetic acid. In the locus ceruleus, copper appeared to be distributed to neuropil rather than glial or neuronal cell bodies, and at the ultrastructural level copper was mainly localized on synaptic membranes of afferent terminals in contact with somatic spines or dendrites of locus ceruleus neurons, whereas copper was distributed to mitochondria in the granular layers of cerebellum and fine, sparse silver particles were observed throughout ependymal cells and epithelial cells of blood vessels. The specific localization of copper to afferent terminals in the locus ceruleus was confirmed by X-ray microanalysis, which showed a significant level of copper, but not zinc, in synaptic membranes. These results suggest a distinct role of copper depending on its regional distribution. Copper or copper protein may be involved in neurotransmission in the locus ceruleus but in mitochondrial activity in the cerebellum.

Animals↗

PubMed1994

Septa in the liver of patients with chronic hepatic schistosomiasis japonica: MR appearance.

OBJECTIVE: Chronic hepatic schistosomiasis japonica is a disorder characterized by broad fibrous septa in the liver. The ability to recognize these septa on MR images might enable distinction of this lesion from other cirrhotic disorders. The purpose of this study was to analyze the MR appearance of these septa. MATERIALS AND METHODS: MR images of 18 patients who had typical calcifications of hepatic septa on CT scans were reviewed. The diagnosis was proved by biopsy in six patients. In the remaining 12, stool examinations were positive for schistosomiasis. T1-weighted MR images and T2-weighted and intermediate (long repetition time and short echo time) MR images acquired with the use of gradient-moment nulling were obtained in all 18 patients. In eight of 18 patients, additional T2-weighted and intermediate images were obtained without gradient-moment nulling. Fifteen patients had contrast-enhanced T1-weighted images. The presence of abnormal MR signal and its intensity at sites corresponding to the septa seen on CT scans were studied. RESULTS: MR images showed the septa as linear abnormalities frequently seen in the subdiaphragmatic portion of the right lobe of the liver. On T1-weighted images, septa had low signal intensity and were identified in nine of 18 patients. On T2-weighted images obtained with gradient-moment nulling, septa had high signal intensity and were seen in 13 of 18 patients. On T2-weighted images obtained without gradient-moment nulling, the septa had primarily low signal intensity and were seen in five of eight patients. On intermediate MR images obtained with gradient-moment nulling, the septa had primarily high signal intensity and were seen in nine of 18 patients. On intermediate images obtained without gradient-moment nulling, the septa had primarily low signal intensity and were seen in four of eight patients. In nine of 15 patients, septa were visualized as high-signal-intensity lesions on contrast-enhanced T1-weighted images. In 14 of 18 patients, the septa were detected in one or more sequences. CONCLUSION: Our experience suggests that MR imaging in patients with chronic schistosomiasis of the liver depicts the morphologic features of hepatic septa. MR signal characteristics of septa are not unique, but use of gradient-moment nulling alters the signal intensity of septa, similar to that of blood vessels, on intermediate and T2-weighted images.

Aged↗

PubMed1994

[Immunohistochemical studies on mycobacteria in tuberculous necrotizing granulomas].

For the purpose to know the pathogenesis of caseous necrosis in tuberculous lesion, authors compared the presence and the number of mycobacteria in the pulmonary tubercles of various histological types. Forty pulmonary tubercles obtained from 16 patients (9 males, 7 females; mean age 51) were examined. By Ziehl-Neelsen (ZN) method, acid-fast bacilli were detected in 40% of 5 proliferative, in 12.5% of 24 productive and none of 11 sclerotic granulomas. By immunohistological staining with anti-BCG antiserum, positive staining was observed in 60%, 87.5% and 91% of each type of granuloma, respectively. Types of necrosis were classified by silver-staining as necrosis after exudative reactions (EN), necrosis after productive reactions (PN) and filled materials after softening and liquification of necrotic lesions (LN). EN was observed in 24 tubercles, and mycobacteria were stained in 8% of EN by ZN method and in 75% by immunohistological method. PN was observed in 21 tubercles, and mycobacteria were detected in none and 5% of such type of necrosis by respective method. LN was observed in 28 tubercles, and mycobacteria were detected in 11% and 71% of these lesions by respective method. So, positive ratio by immunochemical method was significantly higher in EN and LN than in PN. Further, mycobacteria were stained with anti-BCG antiserum as granules and the number of such granules were much more numerous in EN and LN than in PN (p < 0.01). From these results, it was suggested that necrosis might occur by different mechanisms in exudative reactions and in productive reactions.

Adult↗

PubMed1993

W-heterochromatin of chicken; its unusual DNA components, late replication, and chromatin structure.

About 65% of DNA in the chicken W chromosome has been shown to consist of XhoI and EcoRI family repetitive sequences. These sequences showed remarkable delay in the electrophoretic mobility at low temperature on a polyacrylamide gel. Three dimensional structures of the 0.7-kb XhoI and the 1.2-kb EcoRI family repeating units were estimated to be irregular solenoids using a computer program based on wedge angles of all the 16 dinucleotide steps. Fluorescence in situ hybridization demonstrated that these two family sequences were localized in a major heterochromatic body in an interphase nucleus. Incorporation of bromodeoxyuridine into the W chromosome in the synchronous culture of MSB-1 cells occurred about 1 h later than the peak of S phase. The chromatin structure formed along XhoI and EcoRI family sequences was suggested to be different from the total chromatin or chromatin containing the beta-actin gene sequence in that the linker DNA lengths of the former were significantly longer. Fractionation of the HaeIII-digested MSB-1 nuclei yielded a chromatin fraction in which XhoI family sequences were partially enriched. Several DNA-binding proteins showing higher affinity for the XhoI family sequence were present in this fraction.

Actins↗

PubMed1993

Confluent hepatic fibrosis in advanced cirrhosis: appearance at CT.

To determine the computed tomographic (CT) characteristics of confluent fibrosis complicating liver cirrhosis, CT scans of 420 cirrhotic patients without hepatic malignancy who underwent hepatic transplantation were correlated with freshly resected whole liver specimens. In 59 patients, CT demonstrated 70 focal abnormalities corresponding to confluent fibrosis. The lesions were characterized by shape and location: 49 wedge-shaped lesions radiated from the porta hepatis, eight peripheral bandlike lesions were remote from the porta hepatis, and 13 lesions were seen as total lobar or segmental fibrosis. Associated volume loss was seen in 62 of the 70 lesions as retraction of the overlying hepatic capsule or total shrinkage of the segmental or lobar involvement. At plain CT, all 70 lesions were areas of lower attenuation than adjacent liver. At contrast material-enhanced CT, 51 of 64 lesions were iso-attenuating or minimally hypo-attenuating. The authors conclude that confluent fibrosis has a characteristic appearance at CT. Recognition of its characteristics may help radiologists differentiate confluent fibrosis from hepatic neoplasms in cirrhotic patients.

Adolescent↗

PubMed1993

Amyotrophic lateral sclerosis: T2 shortening in motor cortex at MR imaging.

PURPOSE: To determine whether decreased signal intensity of the motor cortex (T2 shortening) at magnetic resonance (MR) imaging is a useful finding for supporting the diagnosis of amyotrophic lateral sclerosis (ALS). MATERIALS AND METHODS: High-field-strength (1.5-T) MR images of 15 patients (seven men and eight women, aged 28-80 years) and 49 neurologically normal age-matched control patients were examined for T2 shortening in the motor cortex. In addition, brains of patients with ALS were examined at autopsy. RESULTS: The MR images of 14 of the 15 patients showed T2 shortening in precentral cortices, while the images of all but one of the control patients showed no such finding. In three of eight brains at autopsy, sections from the precentral cortex showed sparsely distributed, intensely stained astrocytes and macrophages. CONCLUSION: Abnormal iron deposition associated with the degenerative process could be the source of T2 shortening, which is a useful MR imaging finding in the diagnosis of ALS.

Amyotrophic Lateral Sclerosis↗

PubMed1993

Confluent hepatic fibrosis in advanced cirrhosis: evaluation with MR imaging.

PURPOSE: To assess the usefulness of magnetic resonance (MR) imaging in diagnosis of confluent fibrosis in patients with advanced cirrhosis. MATERIALS AND METHODS: Findings on pretransplantation MR images were compared with findings on pretransplantation computed tomographic (CT) scans and posttransplantation gross appearance and histologic findings in 11 patients with confluent fibrosis. In all patients, MR imaging was performed before and after administration of gadopentetate dimeglumine. RESULTS: Nine lesions appeared wedge shaped and involved the medial segment of the left lobe, anterior segment of the right lobe, or both; two lesions consisted entirely of lobar or segmental fibrosis. Associated volume loss in the affected regions was seen in 10 lesions. All 11 lesions were hypoattenuating on non-contrast material-enhanced CT scans. CONCLUSION: Findings on MR images corresponded well to CT findings and gross appearance. MR imaging provided useful morphologic information about confluent fibrosis, but the MR signal characteristics are not unique and do not enable differentiation from hepatic neoplasms.

Contrast Media↗

PubMed1993

Schistosomiasis japonica of the liver: contrast-enhanced CT findings in 113 patients.

OBJECTIVE: The purpose of this study was to determine the findings on contrast-enhanced CT scans in patients with hepatic schistosomiasis japonica and to determine their pathologic basis. MATERIALS AND METHODS: Unenhanced and contrast-enhanced CT scans of 113 patients with histologically proved schistosomiasis were reviewed. Radiologic and pathologic findings were correlated after autopsy in 19 patients. RESULTS: Unenhanced CT scans showed septal calcification in the liver parenchyma in 53 patients (47%) and capsular calcification along the hepatic surface in 29 patients (26%). Twenty-seven patients (24%) had both types of calcification. Fifty-four patients (48%) showed one or more types of enhancement. Septal enhancement (i.e., linear enhancement of hepatic parenchyma looking like septa in the liver) was seen in 52 patients (46%). Forty-seven of the 53 patients who had septal calcification on unenhanced CT scans had septal enhancement on scans obtained after the administration of contrast material. The enhancement was found at sites of septal calcification in 44 patients and at noncalcified sites in 18 (15 had enhancement at both calcified and noncalcified sites). Five of 60 patients who did not have septal calcification on unenhanced CT scans had septal enhancement at noncalcified sites on scans obtained after the administration of contrast material. Amorphous enhancement (i.e., poorly defined and irregularly shaped enhancement) was seen in six patients (5%). Capsular enhancement (i.e., curvilinear enhancement along the hepatic surface) was seen in 12 patients (11%). Histologic studies showed broad fibrous septa at sites of septal enhancement. CONCLUSION: CT findings in patients with schistosomiasis japonica involving the liver include septal, amorphous, and capsular contrast enhancement. Septal enhancement occurs in broad fibrous septa. CT evidence of septal enhancement may suggest the diagnosis of hepatic schistosomiasis japonica, especially when no calcification is seen on unenhanced CT scans.

Adult↗

PubMed1992

[MR imaging of amyotrophic lateral sclerosis].

Magnetic resonance imaging (MR imaging) provides a sensitive method for mapping the normal and pathological distribution of iron in the brain. High field strength MR imaging (1.5 T) was used to evaluate eight patients with amyotrophic lateral sclerosis (ALS) and 49 neurological normal control patients. All eight ALS patients showed decreased signal intensity in the motor cortex on T2-weighted images, while only one of the normal control patients showed this finding. The results suggested that the decreased signal intensity in the motor cortex in ALS was caused by the deposition of iron in this area.

Adult↗

PubMed1992

Immunocytochemical and in situ hybridization evidence for the coexistence of GABA and tyrosine hydroxylase in the rat locus ceruleus.

We have demonstrated the coexistence of GABA-like and tyrosine hydroxylase-like immunoreactivities (GABA-LI and TH-LI, respectively) in the same neurons of the rat locus ceruleus (LC). The profiles of these cells were labeled by alternately immunostaining adjacent sections for GABA-LI or TH-LI by the avidin-biotin-peroxidase complex method or the peroxidase-anti-peroxidase method after perfusion (either Zamboni's fixative or PPG), and observation at light and electron microscopic levels. For light microscopy, pairs of adjacent sections of more than 590 (Zamboni's) and 260 (PPG), and for electron microscopy, 40 ultrathin sections cut from adjacent semithin plastic sections (Zamboni's), were examined. GABA-LI was found in 80% (1,309/1,642 in total) of small and medium-sized neurons, uniformly scattered throughout the LC. Observations unequivocally show that the majority of GABA-ergic neurons are also noradrenergic. Several neurons are neither noradrenergic nor GABA-ergic, while other noradrenergic neurons do not show GABA-LI. It is shown that astrocytes, but not oligodendrocytes, contain GABA. In situ hybridization using a probe DNA fragment of the glutamic acid decarboxylase (GAD) cDNA, amplified by the polymerase chain reaction, detected GAD mRNA signals in many neurons throughout the LC, supporting the presence of a GAD/GABA system in the LC. Multiple "classical" transmitters, including GABA, serotonin, and noradrenaline, coexist in many LC neurons and may contribute to its widely diverging projections throughout the entire CNS.

Animals↗

PubMed1992

Pseudomyxoma peritonei with progressive calcifications: CT findings.

Development of abdominal calcifications due to pseudomyxoma peritonei is rare. The authors present three cases whereby computed tomographic (CT) studies during or after chemotherapy for pseudomyxoma peritonei demonstrated development and progression of punctate calcifications in the abdomen. The clinical and CT findings of these cases are presented together with a brief review of the pertinent literature.

Adult↗

PubMed1992

Congenital absence of the portal vein.

Absence of the terminal portion of the portal vein and its intrahepatic branches was demonstrated in a 22-year-old woman with focal nodular hyperplasia (FNH) of the liver. Various imaging studies and angiography showed that the portal vein entered into the inferior vena cava just above the renal veins. The clinical and radiological features of this patient and nine previously reported cases of this entity are herein reviewed.

Adult↗