Biomedical subjects
Publications and source records attributed to N Yashiro.
A urachal tumor occurring within a cyst of a 37-year-old man is presented. The tumor was examined by computed tomography and magnetic resonance imaging. Sagittal scans of magnetic resonance imaging were most useful to diagnose the urachal cyst and determine the extent of the tumor.
A case of retrocaval ureter associated with double inferior vena cava, an exceedingly rare venous anomaly, is reported. This anomaly was correctly diagnosed by CT. CT after intravenous contrast injection showed the double inferior vena cavae on both sides of the abdominal aorta and the right ureter crossing the right inferior vena cava posteriorly. CT is a good diagnostic modality with which to demonstrate such a vascular anomaly, and the clinical usefulness of CT is stressed.
We developed a multi-purpose catheter for visceral arteriography. The outer diameter of the catheter is 5 Fr and the inner diameter admits a 3 Fr catheter. The catheter is made of soft nylon, with a shaft enforced with stainless wire mesh to improve torque transmission. The head is shaped into a three-dimensional configuration, enabling the superselective catheterization that is required for interventional technique as well as arteriography of first-order branches of the abdominal aorta, e.g. the celiac artery and superior mesenteric artery. Using the catheter, we performed 275 arteriographies in 100 cases (first-order-branch arteriography in 190; superselective technique in 85). Arteriography of first-order branches was successful in all cases. The superselective technique was successful without using any other catheters in 89% of cases.
Transcatheter arterial embolization (TAE) was performed in 20 patients with ruptured hepatocellular carcinoma (HCC). Bleeding was improved in all patients, but only four survived for over three months. Rerupture occurred in seven patients (35%) and the prognosis was extremely poor. TAE should be considered the treatment of choice for ruptured HCC; however, long-term survival was limited to those patients without portal extension of HCC. The severity of rupture also influenced the prognosis.
In seven primary liver cancers (HCC 5, CCC 1, mixed 1), MR images (0.35 Tesla super-conducting) were compared with macroscopic appearances, and relaxation times (T1 and T2) with microscopic characteristics. MRI was able to reveal the gross appearance of five nodular lesions, but did not reveal one diffuse HCC and one nodular HCC with marked extracapsular extension. T2-weighted SE images could not demonstrate fibrous capsules around the tumor in four nodular HCCs. The T1 and T2 values of the tumors were longer than those of the surrounding liver parenchyma, and the T1 elongation corresponded roughly to the degree of necrosis and fibrosis within the tumors.
Among 224 hepatomas treated with transcatheter arterial embolization, ten patients who survived for three years are presented. All cases had nodular lesions and the volume ratio of tumor to liver was less than 10% in nine cases. Eight cases had no large venous extension, however, one had 90% occlusion of the portal trunk and the other had tumor thrombus within the inferior vena cava. Laboratory data showed liver function was largely spared in eight cases, whereas the other two had severe liver cirrhosis. CT and/or angiography showed an increase in tumor volume in eight cases after three years of survival. Beneficial factors for long-term survival and the limitations of embolization are also discussed.
Dynamic magnetic resonance imaging (MRI) was performed in two patients with hepatic tumors (one cavernous hemangioma and one hepatoma). A sequential timed scanning technique with spin echo images (TR: 100 msec; TE: 20 msec; data acquisition time: 26 sec) was used with a bolus injection of 0.05 mmol/kg gadolinium DTPA. Dynamic MRI findings in the two cases were similar to those obtained with dynamic CT and angiography using iodinated contrast medium. Our early experience suggested that the less invasive technique of dynamic MRI could replace conventional dynamic CT in assessing the hemodynamics of hepatic tumors.
Among 123 cases of hepatic cavernous hemangioma examined by CT, MRI, and/or angiography, four were considered atypical from the viewpoint of differential diagnosis on individual modalities: two cases of nonenhanced tumor, one of diffuse, homogeneous staining and rapid disappearance associated with arterioportal shunt on dynamic CT and/or angiography, and one with a large, internal, high-intensity area on MRI. Although hepatic cavernous hemangiomas are usually accurately diagnosed by the various imaging modalities, some show atypical features.
Spin-lattice (T1) and spin-spin (T2) magnetic relaxation times of 25 human renal cell carcinomas and their assorted normal tissues were measured with a Bruker NMR spectrometer operating at 20 MHz. The tissue samples were examined within four hours after surgery. The results (mean +/- SD) were as follows: renal cell carcinoma, T1 = 638 +/- 168 msec and T2 = 109 +/- 41 msec; normal renal tissue, T1 = 594 +/- 165 msec and T2 = 100 +/- 24 msec. These results indicate that there was no significant difference in T1 and T2 between normal renal tissue and carcinoma. Our results suggest that it is difficult to separate relaxation times of renal cancer from those of normal parenchyma and that the difference between T1 and T2 alone does not permit recognition of renal cell cancer. Paramagnetic contrast agents may be useful in MR imaging to differentiate renal cancer from normal parenchyma.
A patient with acute myelocytic leukemia recovering from hepatic candidiasis after long-term administration of amphotericin B had large scar in the liver which showed prominent prolonged enhancement on postcontrast CT. Prolonged enhancement can occur in regions other than hepatic masses.
Five cases with primary Budd-Chiari syndrome due to membranous obstruction of the hepatic segment of the inferior vena cava were examined by CT. In all cases, CT demonstrated caudate lobe enlargement, reticular low density within the liver parenchyma, splenomegaly, and collaterals via the ascending lumbar veins and azygous system. Pathological study revealed liver cirrhosis or fibrosis in all cases. In two cases, calcification was shown in the region of the hepatic segment of the inferior vena cava. Our results suggested that the CT appearance of primary Budd-Chiari syndrome was rather characteristic and useful in diagnosis, although membranous obliteration could not be shown directly on CT.
Four cases of traumatic renal artery occlusion are reported. A direct blow to the abdomen was considered to have caused renal artery occlusion in two cases. They were severely injured and had macroscopic hematuria. Aortography revealed an abrupt cut-off type of obstruction of the renal artery. In the other two, a rapid decelerating-type of injury resulted in damage to the intima of the renal artery. They showed almost no outward signs of injury and no macroscopic hematuria. Aortography disclosed a tapered occlusion of the renal artery. CT showed the rim sign between the seventh day and sixth week before the compromised kidney became apparent. It had disappeared by the time follow-up CT revealed contraction. One patient developed hypertension, which subsided after nephrectomy. CT findings of the patient suggested the possibility of predicting hypertension as a sequelae of acute renal artery occlusion.
Intraarterial digital subtraction arteriography (IADSA) was performed in 94 patients with hepatic tumors and evaluated on the following subjects: 1) visualization of small arteries in arterial phase, compared with film study, 2) visualization of faint tumor stains in hepatogram phase, compared with film study, 3) visualization of portal venous branches by intraarterial digital subtraction portography (IADSP). Interventional angiography was performed in 76 patients. Contrast dose and injection rate of IADSA was approximately a third of film study without dilution. The position of the catheter was identical in IADSA and film study. IADSPs were performed with 15-20 ml of 76% Urografin, which was injected into the superior mesenteric artery at the rate of 5 ml/sec after infusion of prostaglandin E1. Comparison in arterial phase of 67 patients showed 24 (36%) IADSAs were equal to film study. Thirty-nine (58%) were inferior but adequate for the diagnosis of hepatic tumors. Comparison in hepatogram phase showed 24 (38%) IADSAs were superior to film study and all were satisfactory for the diagnostic purposes. Ninety-eight percent of 86 IADSPs gave information about the patency of the main portal vein. Fifty-five percent of IADSPs opacified third-order portal vein branches or further. IADSA of hepatic tumors not only save time and contrast dose but was also satisfactory in image quality for interventional angiography.
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Transcatheter embolization has recently gained widespread acceptance in the treatment of a variety of conditions. To clarify the localization of therapeutic gelatin particles, we have described a simple and safe technique of labeling gelatin particles with 99mTc using stannous chloride solution. This technique provides satisfactory labeling efficiency and allows excellent scintigraphic images of therapeutic gelatin emboli, thus making it possible to clarify the localization of the injected embolic material in vivo.
CT and angiographic features of nine incidentally discovered small renal adenocarcinomas are reviewed. They were all discovered by CT or US during screening procedures or examinations targeting the liver or pancreas. In our institute, they constituted 56 percent of renal adenocarcinomas whose diameters were 4 cm or less. CT without contrast enhancement detected abnormality in seven of the nine, but two were negative or equivocal. Postcontrast CT delineated all tumors as relatively low-density areas, since the normal parenchyma of the kidney showed intense contrast enhancement. We believe that isodense or nearly isodense masses that show relatively low density after contrast are diagnostic of small solid renal tumors. Dynamic study with a bolus injection of contrast medium added information about the vascularity of the tumors. Angiography revealed hypervascularity in only four of the tumors. The rest were avascular or hypovascular. Four tumors that were avascular in the AP arteriographic view were shown to be hypovascular by a tailored oblique view in which adequate obliquity of the angiographic projection was determined by referring to CT, so that the tumors would be seen in profile and would not be superimposed on by normal parenchyma or vertebral shadows.
MRI can visualize bone marrow more clearly than X-CT or RI because the bone generates weak signals whereas the fat in the marrow gives strong signals. We described diagnosis of various bone marrow disorders by MRI technique. Hyperplasia of bone marrow decreased fatty cells and resulted in prolongation of T1, whereas hypoplasia of bone marrow replaced hematopoietic cells with fatty cells and resulted in shortening of T1. In aplastic anemia, the localized hyperplastic areas in abnormal fatty marrow can be visualized. In bone tumor and metastasis to bone marrow, T1-weighted IR image can provide the best contrast between the tumor and normal marrow, although neoplastic and inflammatory lesions can not be differentiated by MRI. In iron storage diseases, MRI can detect early changes by its higher sensitivity to iron than that of X-CT. MRI may be usefull in monitoring bone marrow damages noninvasively to patients under radiation and/or anticancer drug therapy.
A case of mucolipidosis II (I-cell disease) in the early neonatal period is reported. The infant showed severe skeletal changes including diffuse periosteal new bone formation of long bones and ribs, marked osteopenia, resorption of scapula, clavicula, and mandible, and irregular demineralization of metaphyses of long tubular bones. Early skeletal manifestation of mucolipidosis II is not well known and differentiation from congenital syphilis or congenital hyperparathyroidism may be difficult. In such cases, a radiologist should assist in the diagnosis, and the list of differential diagnoses should include mucolipidosis II.