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Biomedical subjects

K Ohtomo

Publications and source records attributed to K Ohtomo.

At least 181 records · Page 10Linked to original sources
PubMed1986

"Ductectatic" mucinous cystadenoma and cystadenocarcinoma of the pancreas.

Five cases of localized cystic dilatation of a side branch of the main pancreatic duct due to a new entity ("ductectatic" mucinous cystadenoma and cystadenocarcinoma) are reported. The dilated duct was widely covered by epithelium indistinguishable from that of mucinous cystadenoma (n = 4) or cystadenocarcinoma (n = 1) of the pancreas. All lesions were located in the uncinate process and were about 3 cm in size. On computed tomographic scans and sonograms, lesions were difficult to distinguish from simple cyst of the pancreas unless lobulated or irregular margins were demonstrated. Endoscopic retrograde pancreatography (ERP) or operative pancreatography clearly demonstrated characteristic findings: localized, prominent cystic dilatation of a side branch of the main pancreatic duct with grape-like clusters or pear-shaped pools of contrast material associated with filling defects of various sizes. When a cystic lesion is noted in the uncinate process of the pancreas, ERP is mandatory to confirm or rule out this potentially or overtly malignant disease.

Aged↗
PubMed1986

Immunohistochemical studies on the GABAergic system in the rat supraoptic nucleus using the PAP method with an application of electron microscopy.

GABAergic neuronal profiles in the supraoptic nucleus of the rat were immunohistochemically identified by using a purified GABA antibody with the peroxidase-antiperoxidase method. The localization of GABA-like immunoreactivity in nerve terminals on the neurosecretory neurons was examined electron microscopically. A few small GABAergic neurons were found inside the supraoptic nucleus while only a very few medium-sized ones were detected in the perinuclear zone. Intrinsic, non-GABAergic small neurons covered by GABAergic neuropil were also detected. The neuropil with GABAergic axo-somatic synapses evenly encompassed unlabeled neurosecretory perikarya throughout the supraoptic nucleus. The GABAergic system seems to inhibit both vasopressin and oxytocin cells. In this area, glia cells showed clear outlines of unlabeled somata around counter-stained nuclei. Blood capillaries in the supraoptic nucleus were only slightly covered with a GABAergic neuropil. Electron microscopic observations demonstrated the presence of GABAergic axo-somatic symmetrical and axo-dendritic asymmetrical synapses on the neurosecretory neurons. GABA-like immunoreactivity was localized on the membranes of microtubules and synaptic vesicles, on the external membranes of the mitochondria, and on the inner leaf of the presynaptic sites. Numerous pairs of non-immunoreactive synapses were arranged along these immunoreactive synapses.

Animals↗
PubMed1986

Dynamic CT features of arterioportal shunts in hepatocellular carcinoma.

Dynamic computed tomographic (CT) findings of 42 patients with hepatocellular carcinoma having angiographically proven arterioportal shunt were reviewed. CT findings related to arterioportal shunt were as follows: early enhancement of the portal vein, which showed a time-density curve similar to that of the aorta, markedly prolonged enhancement of the portal vein, dilated, abnormal intrahepatic vessels often accompanied by irregular, transiently enhanced areas, transient high attenuation of lobar or segmental distribution in the lobe contralateral to the main tumor, and transient wedge-shaped enhancement peripheral to the tumor. Dynamic CT usually detected arterioportal shunts involving larger portal veins as represented by any of the first four findings (14 of 17), whereas detection of arterioportal shunts involving smaller portal veins was lower in frequency (8 of 25), but such a shunt could be demonstrated as transient wedge-shaped enhancement peripheral to the tumor.

Arteriovenous Malformations↗
PubMed1986

CT of hepatic masses: significance of prolonged and delayed enhancement.

Hepatic masses showing higher density than that of liver after 3 min (prolonged enhancement) and/or having prominent enhancement after the arterial-dominant phase (delayed enhancement) of dynamic CT (bolus enhancement followed by serial scans) were reviewed. Prolonged enhancement was noted in any hepatic masses, but mainly in cavernous hemangioma and capsule of hepatocellular carcinoma, whereas delayed enhancement occurred in capsule of hepatocellular carcinoma and occasionally in metastatic tumor. The volume of arterial and portal blood supply, turnover rate of blood, extent of the interstitial space, and diffusion rate between the vascular and interstitial space, as well as dose and speed of contrast agent administered, seemed to be important factors in such contrast enhancement. Prolonged enhancement and delayed enhancement are nonspecific but still are of some value in the differentiation of hepatic masses on dynamic CT.

Biliary Tract Neoplasms↗
PubMed1985

Hepatic tumors: differentiation by transverse relaxation time (T2) of magnetic resonance imaging.

Fifty-three patients who had hepatic tumors (24 hepatomas, ten metastases, and 19 cavernous hemangiomas) underwent MR imaging using a 0.35-T superconducting imager. The transverse relaxation time (T2) was calculated from a pair of spin echo images (repetition time [TR] of 1600 msec) with echo delay times (TE) of 35 and 70 msec. The computed T2 value was obtained in a fashion similar to that used to obtain CT numbers with region-of-interest cursors. The mean T2 was 59 +/- 9 msec in hepatomas, 64 +/- 15 msec in metastases, and 100 +/- 30 msec in hemangiomas. The difference between the T2 of hemangioma and that of liver malignancies was statistically significant (P less than .001); however, differentiation between hepatoma and metastases was not possible. The T2 was shorter than 80 msec in all 24 hepatomas and in nine of ten metastases, and was longer than 80 msec in 16 of 19 hemangiomas. Forty-nine of 53 cases (92%) were correctly classified when the borderline of T2 between hemangioma and hepatic malignancies was set at 80 msec. MR with T2 calculation was valuable in differentiating between hemangioma and hepatic malignancies.

Carcinoma, Hepatocellular↗
PubMed1985

Solitary renal hamartoma not associated with tuberous sclerosis: roles of CT and angiography.

CT and angiography of five solitary renal hamartomas not associated with tuberous sclerosis are reviewed. CT revealed fat in four hamartomas and was the more reliable in the differentiation from renal cancer. Bleeding from the tumour was detected in two cases and the extent of each haematoma was precisely determined by CT. Angiography showed specific findings in only one tumour. In a pararenal hamartoma, angiography was of value in clarifying the renal origin of the tumour. Though angiography may be of help when CT is inconclusive, we think it should not be relied upon as a major diagnostic tool and we utilise it mainly for preoperative mapping and embolisation. In one case CT did not detect fat and preoperative diagnosis was impossible. In one case with haematoma, detection of fat was difficult. We believe potential hamartomas with no detectable fat should be treated as malignancy until proved otherwise. There seems to be discrepancy between the vascularity of the hamartoma and the degree of contrast enhancement (CE) with a bolus injection method; hamartomas seem to show weaker CE than that expected for renal cancer of equal vascularity, a fact which may differentiate solitary hamartoma from cancer.

Adult↗
PubMed1985

Noninvasive diagnosis of small cavernous hemangioma of the liver: advantage of MRI.

Thirty-three lesions of small cavernous hemangioma of the liver under 3 cm in diameter detected by sonography, computed tomography (CT), or magnetic resonance imaging (MRI) were reviewed. Sonography detected 23 lesions, plain CT 15 out of 26, and MR 31, including one equivocal. On sonography, 18 of 23 revealed a strong, almost homogeneous hyperechoic mass without a rim. On CT, eight of 33 showed characteristic findings of hemangioma by contrast enhancement. On MRI, 26 of 31 appeared as a markedly high-intensity area, which was rarely the appearance of other hepatic tumors of similar size. Spin-spin relaxation time (T2) of hemangioma was prolonged over 80 msec in 15 of 18 while one of 20 lesions in patients with primary or secondary liver cancers under 3 cm showed T2 of 80 msec or more. MRI in addition to sonography and/or CT allowed detection of almost all cavernous hemangiomas over 1 cm in diameter and diagnosis with considerably high accuracy and specificity. MRI will play an important role in determination of necessity of further invasive diagnostic methods for patients with small liver tumors detected by sonography and/or CT.

Angiography↗